Don't get sucked in paying more than you need to. Check on this site (often), the parts will come in and quickly get snatched up in a few days. Don't get scammed or pay double on eBay, the 10 round poly-mag should be bout $35 or so. Don't buy from any site that takes crypto as payment but doesn't take credit cards - they are scams.
CZ parts
There's also a place in the Czech Republic that apparently buys parts and ships to the USA, as well as another company in UK that is apparently good too.
I love my CZ 457, really nice shooter, and a step up, IMO from the several 452's I have (they are still good, of course, but the 457 is the better buy).
Only thing I didn't think much of is the plastic cocking indicator, so I made my own. The 457's bolt handle is fairly easy to change, here's one I made from black Delrin.