In-Wall or In-Ceiling speakers can range anywhere from $30 to $3,000 per pair and sound quality will vary accordingly. Companies that specialize in custom installations like Sonance, Niles, and Audiosource would be a good place to start. I have heard some very nice installations using Sonance. You should also be able to find products from more mainstream vendors such as Polk Audio, Boston Acoustics, or Cambridge Soundworks in this price range. Another option might be Gallo micros. These are very nice when paired with a sub. There is a pretty good selection on eBay if you feel up to a little adventure.
Good luck.
Brady
Good luck.
Brady