For under $650 the first one that comes to mind is a full size glock gen 4 with the interchangeable backstraps.
ORRRRR a full size revolver in .357 mag if you don't want to use commie plastic guns.
I did want the .357 initially but I figure I'll buy the semi auto now and save the less banable revolver for later.
From what I've been reading the Glock 17, Ruger SR9 and an XD are within my price range. I hear the SR9 is slim but I might be ok with that; my main issue was length of the grip. I'm hoping a local shop will have all three in stock for me to get a feel for.
ETA: The .357 was going to be for a sidearm for a hog hunting trip I got invited on. Other than that I realize the Glock/Ruger is much more practical.
This post was edited on 1/25 at 2:48 pm