They're hard to find and I don't know that they'd sound good for HT, but the Linn Kan Mk II's are designed to at least be put close to a wall if not actually on a bookshelf. They're very musical and very small. They usually run about $450-500 a pair used, so you could get 4 for your target price.
We're not giving you marriage advice, we're giving you audio-nut advice. It's a lot like golf-nut advice - if you want to pursue it with any real vigor, you're going to have to put up with a lot of potential friction with your significant other. Might as well brace yourself for it, but don't let it ruin your fun. -Kirk