9mm single stacks
Kel-Tec PF9
Ruger LC9
Kahr CM9
Kahr CW9
Walther PPS (a little over budget)
Another option is a Ruger SR9C, which is relatively slim for a doublestack.
I don't own a Ruger SR9C, but have shot one and was impressed. I have read good things about it on line, and I think the price is right, maybe used. Only thing I do not like is the manual safety (if I'm recalling correctly) but that's just because I like simple, for the complete idiot (me).