Another vote for the CZ 452, but I have never handled the 455 or 457. If you do not like the trigger guard on the 452 you can get a more pleasing to the eye trigger guard. Also if you can find a really clean Brno (the company before the name CZ) you might like it a lot. Someone on this site was offering a CZ Super Brno for sale. This is a very nice rifle if you want the longer barrel. I do not think you have a chance of finding a 453 for $500. Lots of people report their CZ likes Wolf ammo which is about $6 a box. Wolf changed their place of manufacture a bit ago. I have not tried the new production.
The wood on a 452 is better than it appears with the CZ finish on it. I have seen some stripped and refinished. They can be beautiful. Sometimes the triggers are excellent right out of the box and if not a simple Yo Dave trigger job (www.rimfirecentral.com) can bring it into shape for about $20 or less.
i warn you that acquiring one CZ is the start of wanting another. Currently the 457 Youth Version in 223 is being closed out and can be had for about $440. This is a steal. The rifle reminds me of the Mannlicher 1903 in feel. For a moment the 457 full stocks were being closed out and sold cheap, but they appear to have been sold. The prices have been going up.
The 452 American will require optics. Others like the full stock will have iron sights and one can mount a scope if desired. The 452 full stock will sell for a premium if you can find one. A NIB 452 American might be challenging to find.