I guess it all comes down to what region you're in. I don't see many old K frames in my area that are in decent shape or bargain priced. I bought some armor car company model 64 and model 10 trade-ins a couple years ago and paid $250-275 for each of them. (When no one could find any 9mm around, I thought it would be a very good idea to have a few more 38 Special wheel-guns). I don't see those kind of prices on guns in comparable shape today. (I haven't been looking hard since I have what I need already, though.)
I also remember how cheap 28s were. You saw them in the LGSs all the time, and they usually just stayed in the glass case. Not a lot of customer interest.