@davidmace
Years ago, about ~1998-1999 I had a loaded out A500. It was a lot of fun and back then with amiga prices still relatively high it was what I could afford for a hobbyist computer. There are a lot of limitations with with a loaded A500 compared to it's big box brothers. Keep this in mind as a consideration before you dump big bucks upgrading.
It all depends what you want to do. If you want to upgrade to the point you can ue major internet apps, consider picking up at least an A2000 instead.
Hmm.. Back in the day there were no clockport adapters for the A500.. Now there are, and I am salivating thinking how much I would have LOVED to have a Silver Surfer on my old A500 set up :-( Darn, you guys make me want to buy another Amiga! :-/