Its really hard to give a ballpark prices based just on models you are asking about. K31 can be 700, it can also be over a grand. Depending on condition and goodies it comes with. RC 98's go for around 650-1100. Again, price will depend on condition, state of "de-nazification", year, presence/absence of assesories etc. For example, I paid 550 for my bush gun I use during WW2 reenactment. 1944 made in Czech, dinged up with dark bore and 1100 for mostly matching 1938 with bright bore, no RC X's, mostly matching German made one. Non RC price range can be between 1500 and god knows how much, I've seen people asking 3500-4000. Sometimes people score really nice specimens at gun shows. A friend was looking for RC 98 to use for reenactment but ended up walking away with all matching verified Mosin sniper for 700 but that does not happen often. Most people know what they are selling.