Posters for Sale

A reader contacted me today asking for advice on where to buy inexpensive posters or prints by Japanese illustrators (he was comparing to the price range of these Kozyndan posters). I’m not quite sure where the best place would be, so I thought I’d make this public, to get some responses. I know that a lot of exhibitions sell them, in relation to the show that’s on (the Mori Art Museum is probably good for that), but anything else? Nadiff would seem like a good place, but I can’t really remember if they sell posters, since it’s not something I’ve looked for.