I'm afraid you've fallen in with a bad crowd here.
Here's my advice - leave here and don't log in again
Seriously. We're all maniacs. The advice you'll get here will not make your wife happy. It will cause you to spend much more than you though you'd ever spend.
I mean it. Log off. Have the builder run you some wires, drywall the room, and you can get a nice projector, maybe some new speakers at Best Buy.
There's no other way to put this: we're serious geeks about this. That means that no home builder will meet our standards and understand our obsession. We represent a very small niche market. And as I said, we're all pretty much nuts.
But if you really want to dig into it, you'll find some very nice, extremely helpful people here. We'll help you empty your bank account, too! We are the holders of some very interesting secrets, but as I said, learning about them will be expensive.
I spent over six months just planning, asking questions, and talking with people here online, then another eight months building. My wife doesn't want to know what I spent (it's a good thing she doesn't). And our family is very happy with our theater. It's an amazing space and we love to entertain and to use it ourselves almost every day. There's nothing like experiencing a movie in a well designed and executed home theater.
I'm sorry, but your builder can't do it. Even if he says he can. He just won't have the experience or the knowledge to design and build a proper acoustic environment. It's not as simple as putting up some drywall.
Most people are very happy with their simple home theaters without going to the lengths that we go to. But if you ever get a chance to visit one of our theaters, you'll know why we've gone slightly off kilter about the subject.
Good luck to you!