The 53 stamped ammo is military surplus, and loaded pretty hot. It is corrosive, so you will have to clean the pistol after every range trip. The brass is also somewhat brittle, and you will experience cracked necks in the cases. I have seen 1 or 2 cracked necks in each 8-round magazine. Don't count on reloading them, they are Berdan primed, so difficult to reload even if the brass wasn't brittle. I wouldn't hesitate to shoot the stuff, but I wouldn't buy it, either.
I think I paid $175 for my CZ52, about 8 years ago, and it appeared unfired. I don't know what they sell for now, but double $175 wouldn't surprise me.