The best place that I've found for cheap art is online. One Day Gallery has the best prices that I've found and definitely a great variety. http://www.OneDayGallery.com
Best Cheap Art Dallas 2009 - Urban Outfitters at Mockingbird Station
A piece of art large and bold enough to set the desired tone in the living room can be pricey indeed. That's why in these spare times we recommend checking out Urban Outfitters when you find yourself in a decorating pinch. There are large-scale paintings—granted, they're not original oils, but come on, don't be difficult—for $60 to $100, and they're pretty cool. A recent visit turned up canvases showing a bright green tree with broad, gnarled branches, black and white renderings of urban bridges, and a helter-skelter pile of books from a wacked-out vantage point. If you want to set off the colors in whatever piece you choose without making another stop, pick up some Indian-embroidered throw pillows to complement the art.