I have never seen the A500 go for more than around $150, a lot of them way less on ebay.
There is a "tulip mania" going right now with Amiga and others. I got back in this last year and prices weren't like what they are now. It will go back.
Then there is my good fortune from a few weeks back getting a few amigas, software, peripherals for $50. He was going to the recycling center if I didn't take it.
He knew what he had, wasn't naive.