Friend has one of the Russian Maks with the adjustable sites. Had it for several years, He is considering selling it.
Assuming good condition, what's the current street price on these?
about $200 is a fair price for pistol and 1 mag.
mags are about 10 bucks a pop, ammo is about $10/50, holster with cleaning kit in good condition would be worth about $15.
if its REALLY nice, and comes with a ton of stuff, i might go as high as $300.
YMMV

Like Rockstar said, around $200. And that would be for a clean one. The only way I would venture anywhere close to $300. would be if it were a double-stack Makarov with a couple of original 12 round magazines.