The only bolt rifle I could find in 7.62x39 (other than custom rifles out of my price range) was the CZ 527 package (w/ poor scope) at @$500+ and the Ruger MKII limited edition (no scope) at @$550+. Maybe there are others, but I couldn't find any on Gunbroker, Auction Arms, Guns America, or any local shops.
The CZ has only an 18.5 inch barrel, which further weakens an already mild cartridge for deer. It also adds kick and blast that I don't desire in this rifle (for obvious reasons). It would need a new scope of better quality (for my standards), so add the scope price to the $500+.
The Ruger is a nice rifle, stainless, but to the $550 price add drill and tap + good mount = $75 minimum, plus the scope price as above.
MGM: My gunsmith didn't say anything about needing a new bolt. The bolt extractor (the only part critical on the bolt face) is larger on the 8x57, but it reaches to about .412 diameter when closed. The outside diameter of the 7.62x39 base is .447 (inside is .376), so it is catching about half the base. It's not a perfect fit, but it is good enough to get the job done. I won't be shooting any hot handloads (factory ammo at $2 a box), so I doubt I will ever need the full catch to extract a spent case. I've tested the bolt on an unfired 7.62x39 case and the catch seems satisfactory. Anyone please correct me if I am misguided here.