one of my favourite things to do whenever i visit an art museum of some kind is to browse the gift shop and see what cool posters they have for sale. there are almost always really different and well designed graphic treasures to find, as well as the classic art exhibition posters (think Matisse, Picasso etc) that can really have an impact on your home decor without spending too much cash. i found the Vintage Poster Company on Etsy and they have some really unique posters in their shop, many i have never seen before. besides the requisite vintage travel posters that are always so cool, they have a lot of art exhibition posters and a cool section of Polish posters that have this sixties Heinz Edelmann (of the Beatles fame) feel to them. i picked some of my favourites here but their entire shop is worth a browse.