Check DJs Pawn Shop in Bothell. They have a big selection of used firearms, and they have a lot of stuff that's not on display - It says Pawn Shop - but it's about 98.9% firearms. The actual pawn shop stuff consist of a small counter of jewelry and a closet sized area of tools. If you want new, I'd check Mary's Pistols in Tacoma (pretty much what is says - all pistols), and Surplus Arms and Ammo in Lakewood ("black" rifles and tupperware mostly). It's always fun to walk through Sportsmen's Warehouse in Federal Way, but unless they're having a sale, they won't have the best price.