There are few pawn shops in my state and they can't sell firearms. There might be a connection there, but that's not my point.
When dealing with one of the two LGS that I usually buy from, I ask if the tagged price is the best they can do. One shop rarely offers a discount, the other it depends on whether it's a trade in or a consignment. They have more flexibility on trade ins. They do not offer any discount on new guns, because the markup isn't very high. I've heard that at a few different shops, so I'll take it to be true.
I never trade in a gun to a LGS, the numbers don't work well IMHO. As with trading in your used car towards a new one, the chances are great that the LGS will make more on the trade in than on the new gun/car.
I don't begrudge them their profit, not at all. If they don't make money, they'll go out of business and I don't want that. OTOH, I can generally figure out what a fair asking price is based on information I garner here, other forums, and of course online auction sites.
My son has done very well buying tools at pawn shops. Apparently some people on the trades will pawn their tools when work is slow and then (hopefully) pay off the loan and get them back when work picks up. He gets the tools of the guys that weren't able to do that, and he's a good shopping and sharp negotiator.
The pawn shops where he used to live in AL had a wide range of guns, some good, most new, some junque. He's in SC now and hasn't had a chance to scope out the pawn shop/gun store situation yet. I was hoping to do some of that with him this trip, but we ran out of time. Maybe next time.
If I lived in an area where pawn shops sold guns, I'd make it a habit to "ride the circuit" looking for 3rd Gens!