The only real question you should ask yourself...

...if you feel the photographic fire burning inside you : do I spend 3000$ upgrading my gear to full frame SLR and XMAS, or do I spend that money on the real stuff, medium format film gear?

Ok I should have said "the only real question in case you are about to buy a full frame camera and feel the photographic fire burning inside you", but that'd be less catchy.
If you don't have a DSLR at all, get one. It's so convenient, gives you room to practice etc. It's not sufficient to fully explore the scope of your photographic potential, but it's a must have.

Back to Ze Biblical Question of our times: full frame or medium format film?

That is pretty clear to me:

• If you shoot sports, wildlife, porn or anything that moves, get a full frame DSLR. 
• If you shoot portraits, landscapes, and a lot of black and white get a medium format film camera.

Remember, a full frame SLR sensor is 36x24 mm, medium format film is used up to 60x90mm. When we know how crucial sensor / film size is, it makes you think twice about going 35mm. Also keep in mind photography was originally large format, and 35mm was only invented for portability. It's like CD and MP3, no one listens to CDs anymore, but quality remains on the CD side.

Good luck getting those results with a digital camera, and it sucks you can't see the large prints, the tones, dynamic range, definition.

 Courtesy of Pierre Herbert, Rest in Peace.

Now remember, I made the assumption you are a photography junky, you love the cause, you'd sell your PS3 to replace a lens. If you don't have that level of dedication, forget about film. You'll always be a 30% photographer then :p, covering 30% of the potential. Mwaaahahaha! I'm mean...and stupid because if you all shoot just digital, I'll be the only pulling amazing portraits. The fact is the real thing is medium and large format film.


What what? but my friends have a 5D MKII and I'm enviouuuus! With the biiig lenses they look soooo seriouuuus and proooo !

Ah...well, sorry you have to compensate for something, but this is about the images, not the how the gear looks on you. Anyway, you look way cooler with a vintage piece of gear than with a 5D.

On the left corner, weighting 3000 to 4000$:

• A great full frame DSLR, the Nikon D700 or soon to come out D800. A D700 now costs 2500$. 
• Prime lenses that matches your expectations of greatness would be the 35mm f2 and the 85mm f1.4 . That costs from 400$ to 900$.
• Or a zoom lens for full frame, matching the D700 quality standards like the 24-70 F2.8, 1500$, for a result that is quite questionable regarding the money.

On the right corner, weighting 3000$:

• Let's go for the top, to mach the other corner, a Pentax 67II, used in mint condition from Adorama or B&H for 1200$
• 2 lenses, a portrait lens, a landscape lens, used from the same shops, 500$ each. Those will DESTROY the best SLR Nikon lenses. I mean destroy even the prime lenses. The zoom lenses, ah ah please, be serious for a sec, it beats even the best Leica M lenses. My Mamiya 200$ lenses already outperform all of that.
• A negative scanner. Yes you'll need that, the Epson Perfection V700 does a great job for 550$.
• Film. A roll developed costs about 8$ if the shop doesn't rip you off. You get 10 shots on it.

You can also read my more complete post on what you need to start shooting film.

So here it is. The second choice is the one that is not guided by marketing or the safe feeling of buying the same as everyone else. It's the choice of passion. I won't even write a rational, just Google sample images.
Yes, you'll have to wait to see your picture, and learn how to expose properly, and the characteristics of each film, and focus manually, but it'll pay off. The shutter sound of a MF camera...oh yeah. You'll be thinking every shot, framing carefully, turn into a perfectionist machine to maximize your ratio of good shots. You'll find the pleasure of crafting, then be impatient to see the film developed. Instead of bombarding a village to hit one man, you'll be the sniper that needs one bullet to hit his target.
The truth is, if you go medium format film for portraits, you won't be able to go back to digital, this I can promise you.

The cost of shooting film.

So you want to shoot film too? Hooray! Good choice but it feels like a lot to buy. You are wondering how much shooting film will cost compared to digital? You are not sure what to take into consideration, the real price of bits and pieces etc ? Well this post's for you.

You can now get this baby for $300.

Well I've been spending plenty of my money on it so I now have a clear idea of how much shooting film costs (donation gratefully accepted). I will compare it to a digital SLR type of budget. Here it is:

1. The camera body: 
• DSLR, from $800 to $30 000 for the best (D7000 is at $1200, Nikon D3X& Leica M9 at $7000 for the best 35mm digital camera, and $30k for medium format digital). 
• A great film 35mm will go from $100 (Nikon FE) to $300 (Nikon F5 = a film D3X) used, and up to $1000 for a used Leica M6. A top of the range, digital killer medium format film camera like a Pentax 67II, a Mamiya 7 or RZ, will cost you from $500 to $1000 used (you can still spend $5K on those babies brand new if you have too much money)
• YOU SAVE FROM $700 TO $29 000
2. The lenses:
• If you have a DSLR from a brand that used to do cameras, no extra cost, find a good film camera from the same brand. I hope for you it's a Nikon DSLR...lot of cheap and great film cameras out there ! (check Adorama, B&H)
• If you start from scratch, you will look at normal DSLR prices for 35mm lenses, high prices for rangefinder lenses (Contax G2 and Leica are your 2 best choices, lenses can cost from $500 to $2000), and here comes the great stuff: ridiculously LOW prices for medium format cameras. Ok it sounds too nice to be true but a 110mm 2.8 for a mamiya RZ costs $300 used....I mean this beast outperforms any fancy Nikon, Canon, Leica 35mm lenses. Get it with a medium format camera, and you have the best performing system possible for $1000 all included, minus of course the convenience of digital.
3. Buying film:
• From $3 to $8 a roll (depending on color, ISO, format: check this link for details on formats)
4. Developing film:
• Negatives only will cost you about the same price as the film, it's a bit cheaper in medium format since you got less pictures (about $5 in average per roll)
• Getting prints to will be more expensive, 36 5x7' images can cost you $12. But if you shoot film, you want to scan negatives instead, not get it printed, so you need...
5. ...a film scanner:
• You have dedicated film scanner (machines meant to scan negatives only, not flatbed scanning, the normal ones). There use to be great ones at prohibitive prices, but with no ones buying them they are not produced anymore, so most actual ones are used or 35mm only. Prices vary a lot, a couple of hundreds is quite a maximum price. 
• You can use a flatbed scanner built for photography. Most people use the Epson ones, or Canons. I would recommend the Epson V700: it performs great, as good as the V750. It's a bit pricey ($450) but you can compensate with the low cost of the photographic gear.

I'll be totally honest: I don't develop myself, I have no time and room for that. But the equipement to do it all, dev. + paper etc is about just as much as the camera + the scanner... get it done. 

The loss of control from not developing yourself, you can get it back when scanning the negs so to be honest, you can do without it for a start.

So let's summarize: 

A DSLR + lens + memory cards= from $1500 to $3000 

A great film camera + lens + scanner = from $350 to $1500 (from great 35mm to top level medium format)

You save from $1150 to $1500, which allows you to buy and develop... about 150 rolls of film :)