I think
lbridges confused you. If you want to print that large on inkjet, then you need to spend $10,000. If you want to do it in a darkroom, yes, you can flip the enlarger and shine it on a wall, or on the floor, for a LOT less money. Alternately you can send it in and have it printed for a very reasonable fee. Also, medium format you do not need to spend that much, a nice little Yashica 124G will provide just as good negatives as a Hassy as long as you do not need to swap lenses. If you do, try a Mamiya or Bronica.
Now to back up a little. 35mm or a 25mp camera will provide you with comparable images (actually, if you are shooting B&W although the resolution will be comparable, the 35mm will provide you with nice grain that the digital will not) and you can enlarge either one of those up to maybe 20x24 and see no image degradation at 12 inches (once again, that is strictly B&W as color has a much smaller LP/MM rating). Any larger than that and you will have to go at least medium format.
Medium format shares a lot with 35mm as far as enlargers, scanners, tanks, etc. If you step up to large format (4x5 at least) you gain massive resolution (if I remember correctly, something equivalent to a 590MP digital camera) but it requires more expensive enlargers, scanners, tanks, etc. Of course you gain much more than just resolution with large format, but that is for a different thread.
From what you have said so far, I would recommend a RB67 or similar camera shooting Ilford Delta 100 pro (subject dependent of course) in 120 size. This would minimize your cost in all areas and provide an excellent image. Heck, for what a 25mp digital BODY ONLY costs you could get the entire medium format setup, darkroom included, and have enough money left over for a nice vacation!
Allan