DMZ2112
Chaotic Looseleaf
the short answer is that yeah, 500 GP is a lot of money (to anyone but an adventurer or someone paying an adventurer).
Okay, this wasn't terribly helpful.
Going by the costs of a daily inn stay in the Basic Rules, and assuming that they've got about a 50% profit margin, a craftsman living modestly in town in your baseline D&D setting lives on about four silvers a day. If you assume his income includes another silver for taxes and savings, 500 gold represents 1,000 days of steady earnings. If you tipped this guy a single gold piece he wouldn't freak out, but he'd be impressed by the generosity.