Welcome to the forum! The change over to Model 10 marking started in 1957. The short barreled guns are not as common as the longer barreled ones and may command a slight premium. Perhaps someone will may have a better idea of the serial number range when model marking started.
A reasonable price is one you won't cuss yourself over six months from now. They've climbed noticeably and sharply the last couple years, as a lot of semi-safe queens have migrated to new and different nightstands.
I can't imagine where the sudden interest in guns has come from, people are more often choosing to be armed. It's had some effect on prices as well as ammo availability.
Very true. A local shop had a c 1982 Model 10 police trade three screw. I was almost interested but they wanted too much for it, $299. I was there again today and it was gone after being on the shelf less than a day, I'm sure someone was stoked at the deal they got on a self defense gun with no regard to the (lack of) collectibility and value.