for the 8mm mauser-
I presume you will be looking for a Yugo 48 or 48a
look for smooth action workings, matching numbers if you can, finish of the blueing, grade of the wood, condition of the inside of the bore, bring a bore light, and if your serious bring a cleaning jag and some patches, so you can swab it a few times if there is lots of cosmoline or crud in it.
price should be around $150, any thing under a hundred be very suspect anything in good shape for 125 should be snapped up!
then get some Yugo 1950 8mm mauser ammo on stripper clips, 15 rnds to a box on 3 stripper clips, around $50 for 900 rnds. Good stuff and accurate! (I'm looking for more actually....) Corrosive, but still easy to clean.