Wall mounted, not in wall, right?
If that's the case think this situation is what the Kef T series
is meant for isn't it? The top of the line for the series, a T305 system has an MSRP of a penny under $2200
and only protrudes 1.5 inches when mounted on the wall.
Before taxes, you should have 800 dollars leftover to find a good receiver to pair with them which is plenty, especially since you only need 5.1 for now. Say you spend $500 on the receiver, which is a fairly nominal price, that's a $2,700 subtotal which becomes 2,970 for everything assuming a relatively sales tax rate of 10%. It's right on budget and they have two lower rungs if that's cutting it a little too close for your tastes.
I haven't really tried Ts personally myself and I'm skeptical of how good a speaker that thin
might sound but as an owner of a (sadly discontinued) 5005.2 set, I can say that Kef does a nice job of making nice sounding smallish speakers. Keeping in mind that you've already said you've got the missus to think about and that you want everything made by one company as to unify the look, I think this higher end home theater in a box is likely your best shot a good sounding, sleek, stylish and virtually unnoticable system which will please you both. Should look almost like it's built right into the home.
Just a thought to consider.