It's going to be right at your limit, but it's hard to go wrong with a walther PPS
A little over $500, but the one of the finest single stacks going. The gun is a compact but shoots like a full size. Easy to conceal and easy to shoot.
A good second choice would be the Springfield XDs.
If you want a full sized gun, the S&W Sigma or Ruger P95 are good reliable guns.