I got the impression he was looking for something under 650... a lot of these suggestions are expensive lol unless you can find a good deal used.
I vote buy an AR15! inexpensive, light, and very concealable!!!
I'm actually joking... but I thought I'd go with the trend of suggesting something that does not meet your criterion.
XD's are nice and M&P's are very comfortable and blocks are blocks...
1911's are not something to skimp on.