GC used to be glorious in the 80s. All kinds of used deals. I loved the one in Chicago on Milwaukee. I always found something used I HAD to have. Most of the GCs now are rubber stamp box stores that all sell the same very limited selection of very common amps and tons of student level guitars. 6 people working none which can answer technical questions. I really don't need them , I usually know more about the gear I am looking for than they do and I'll be telling them the features.
They will only give you like 40% 50% on used gear and sell it for twice as much. So if you have an item that they will sell for $1,000.00 they will only give you $500.00 for it. You'll never get $700.00 for it even though they would clear $300.00 cash, they will not budge even if you used the money to buy something else that they would also make a markup on, they have to make a set percentage coming and going. But at least you can walk in/ trade in (albeit at a loss) there.
Generally if a store won't give me a good deal on my trade, I'll buy online and sell online. If they won't deal with me, I won't deal with them.