Well , they have gone through the roof with supply and demand and have been steadily creeping up over the last 10 years or more. I don't get the Mitchel Mauser deal, other than people with more money then sense , but that would be similar to any auction house.
If I was just looking for a Kar98k to fill a void ,I would look at a Yugo rework as they seem to be more reasonable than the Russian refurbs these days.
And , there would be noway a serious collector would pay more for a Russian Refurb than an original bring back unless for some reason that refurb is a rare example.
For me I stopped buying some years ago when a number of "dicked with " stuff kept popping up all over the place and it became harder to recognize some of the fakes. I'm good with what I got and have slowly let go of a number of items over the last several years.
Good luck