In line with chaim's reqs (new, MSRP < $600):
Kel-Tec P40 .40S&W & P11 9mm
P40 is no longer manu, but were well under price. Could require a little work to get going properly, but once tuned, are good-to-go. And they are light. I own a P40 I bought for $275 a few years back.
AMT DAO Backup (9mm, .40S&W, .45ACP)
No longer manu, but were also well under $600...more like $400 when first intro, then went down to $250. I own the .45ACP. It is reliable with hardball, which is all I want to feed it.
Taurus 651 .357mag
I own the Ti model revo. It has turned out pretty well.
CZ75B 9mm
I don't own one...YET! I will, though. I like C&L.
NOT in line with chaim's reqs (USED):
S&W M10 .38spl
$200, used. Utterly reliable.