There is a time and a place for cheap posters. Bathrooms. Fast-food restaurants. Bathrooms in fast food restaurants. If you are under 18 or a college student please, by all means go to the poster/frame section of IKEA and get that Picasso reproduction that has been Photoshopped to hang over your mom's hand-me-down sofa.
For the rest of you, go buy some real art. Real art doesn't have to be outrageously expensive. For an investment as little as a week's worth of lattes at Starbuck's, you not only could have something that might be worth more someday, but just by buying a piece of art, you also say to the world, "I care about craftsmanship." Printmaking or painting makes for a much better travel souvenir than say, going to France to buy the cheap coffee cup that is Made In China. Why travel if you are only planning on visiting the same stores as your home city, but in a different mall?
This past spring I went to England and as I have always done when traveling, I purposely sought out someone selling REAL art. The Mere Gallery, the store I eventually stumbled upon was mixed in with a bunch of other tourist traps selling reproductions Made In China. With traditional printmaking, which I am a personal fanatic of, everything just pops on the page. The intensity of the inks, the texture of the papers, the slight imperfections of the hand-pulled prints. Yup, I wanna slap 'em all in pretty frames on my walls. By buying real art, we support local artists. We get to hear their stories and make the experience of buying something from them a part of a memorable vacation. We get to enjoy their work for the rest of our lives. Who wants to be looking at an IKEA poster at 90 anyway?