This is a basement for crying out loud! Get a projector!
DIY, FTW!
Build a false wall for say $100. $30 in doug fir, maybe something similar for speaker cloth, eh, remaining $40 for some screws and hamburgers and beer. Secure it to ceiling and/or sidewalls with some big screws. I used 6" screws into floor and ceiling myself (two on both).
About $300 for the screen size that Rat was talking about, if you can make it with DIY Seymour fabric, and that's including the wood and material.
Build some speakers, at about $300 apiece, you can start comparing those to speakers that cost about $2000 apiece.
So, say you've never used a power tool in your life. You can hire someone to help build you these speakers and screen for a couple/few of days and still get a lot for your money, and that's not including any other friendly help you could get there in for free. You could pay that guy $1000, and still be saving a LOT of money. I mean, $1k is not even the savings you would get on the screen itself, let alone the speakers.
These are my opinions, and just avenues I think you should be aware of.
You can leave the speakers unfinished because they can all be hidden behind the wall.
The day you move and need these speakers exposed, you can then choose the stain, veneer, or whatever would fit the room the best.
JVC projectors, FTW. No idea how to DIY one.
Look up GO-NAD!'s build, for a basement theater build up in CA.