The CZs are great shooters, but the safety and magazine hanging out the bottom make them less handy in the field. 77/22s are my favorite, but you will not likely find one for $500, even used, without a lot of luck or persistence. I'd look at the Ruger Americans. They're nicely finished for the price, have iron sights, and according to reports here, shoot pretty well. 10 shot flush magazine too.
Personally, I'd also look at a tube-fed Marlin. They have been made in stainless and will feed shorts, I believe. They may be a bit harder to find.
