Looking for some good cheap speakers? Wiredforless.com bought up a cache of unloved (discontinued) "Carver TS-241S Home Theater On-Wall Speaker System" speakers, apparently part of a plasma-friendly HTIB system. A pair is just $69 (original price was $199/pair) plus $5 shipping, a deal good enough to be featured on sellout.woot.
These are slim, curved aluminum cases with a wonderfully simple (and included) mounting bracket. I bought a pair. At 89 db sensitivity they're easy to drive and play a few db louder than my reference speakers, they're a bit bright, and they require a subwoofer (like any speaker this size). Are they the best speakers I've auditioned? Hardly. I'm not even comfortable recommending them as main speakers without using something to tame the harshness (a tube amp would work wonders, but that would sort of defeat the whole budget nature of the deal). However, they are exceptionally clear, they play loud without distortion, and they look great. At this price, you aren't going to find comparable value, and they're absolutely perfect for adding surround, height, or width channels to an existing setup. I may have to buy another pair.
Update: just to clarify, the case is metal, the drivers are not. It has two 4.25" poly mids and a 1" silk dome tweeter per speaker. Also, the speaker terminals are recessed and do NOT accept banana plugs or heavy guage wire.