I trust no one, and just because it survives in someone else's tank doesn't mean they didn't pick up some disease. Following quarantine procedures is always good advice. Dwarf gold angelfish could refer to a number of fish, but I'm assuming it's a Centropyge species, which can eat lps and be fiesty. Specifically what kind of angelfish would make me think about the price, but if I wasn't looking for the fish, I wouldn't pick it up unless it was already on my radar. It's better to hold in your mind the value of $80 and if you had $80 to spend on anything for your tank, what would it be. Would you spend it on some fish that happened along? Where does it fall in your priorities? It's always fun to dream, but keeping in mind what $80 is worth (a few frags, a new magnetic cleaner etc...) and then see if that's your priority for your tank.