I've never actually bought from them, but I've heard a lot about them.
They're a physical chain of stores in Japan. You can browse their stock online but might want to pounce quickly when you find what you want as things can be purchased in store at any time. I'm pretty sure they'll ship to the US without any sort of middleman. They sell mostly used items, but in Japan a used toy is basically a brand new figure. Sometimes they actually are brand new but have a microscopic dent on the box. They're basically the only option for many OOP figures.