My approach has always been, if it's a quality gun (and that means a Glock), and it's not beat to hell, I'm willing to pay within $0-$50 under retail price for it. A $550 gun new is going to set me back an extra $50 or so on taxes. So yeah, I'm cool with paying $500-$550 instead of $600 for it. Plus, you're helping somebody out that might really need the money. Not to say I won't turn down a better deal, of course.
Everyone wants everything for nothing when you're selling, and everything's thinks what they're selling is worth a fortune when you're buying.
That's just the way things work.
JR1572