I think I'm spoiled being in the Nashville area, but the GC here has some decent mid to high level stuff on the floor, and walls. The used department sucks in regards to bass gear, but their used guitar section is amazing. I think they do that to keep up with some of the smaller'ish "mom n pop" stores in the area like Gruhn, Carter Vintage, Lane, and Rumbleseat that all offer online shopping and more often than not free shipping. That being said, I have found some amazing deals on GC used section on the website and frequent it daily almost. Have never been disappointed with any of the used stuff I bought, but have the option to return if something is squirrely. Thats just my experience though, and after reading some threads on here I may just be lucky lol.
For high end bass stuff, I have been a somewhat loyal fan of Bass Central. I have bought a couple Lakland basses from them. I knew what I wanted and they had them on their site. Called them up, and even spoke to Beaver once. They had them on there site, but they shipped to me directly from Lakland. Took about three weeks. I had the funds on hand and paid in full, but he said I could just put down $500 and pay the rest of the balance when it was ready to ship. Not a lot of places do that.