Went with Rick. At least with him you get what's close to a fair deal on whatever you have.
But Les Gold is very beatable, with the right item. It has to be something he finds interesting, something unusual, and something he feels he knows more about than anyone else. Attack emotion and pride and you've hooked him. Then, ignore the "what's the least you'd take" line, which is an incredibly offensive negotiation tactic. Start by asking a lot more than it's worth and slowly work down. If you have an item you think you can sell for $1000, start at $2000 and don't go down below $1500. Les will lowball hard. He knows he's in a power position in negotiating, and it's pretty obvious how he attacks... he's used to people who are so desperate they'll take anything (he's very much like a poker player with a lot of chips and no real hand, who always bluffs with big bets knowing no one with a smaller stack can risk calling without the nuts). So, no matter what he offers, even if he goes up to your number at $1000, whenever he stops going up... walk. Pick up the item and start leaving the store. Seth, Ashley, Les, all three of them consistently will continue to try to negotiate after negotiations are "over". That's their catch... they know it's their store and when they say 'no' it's over, but if you say 'no' they can always chase you into the parking lot calling out higher numbers. That's the only time you'll get fair value from the Golds, as you're walking away.
Of course, as with any negotiation, you have to be willing to walk away from either Rick or Les or they (or anyone else) will take you to the cleaners. That's how it's done.
Oh, and anyone catch Hardcore Pawn when they tried to be nice? The son bought a guitar from a couple that needed money bad. They wanted $3000, he gave them like $500. After he buys it, he goes online and finds out that it's a very rare vintage and expensive guitar. Calls the couple back on the phone and they come back into the shop. Says "Turns out that guitar was worth more than I thought and I want to make it right with you..." and he hands them $1000. Sure, Seth, quite nice of you, but that's still only half of what they were asking and they're still deep in the hole and stuck in their situation. Guy acted like the savior all episode and preened about his good deed. Couple is still screwed.