Hey I just started working on a couple of small dios and vignettes, and I needed some bases. I happened to look in the craft section at Wal Mart and found some various size/shaped wooden plaques for 97 cents (typically, 6" round, oval, rectangular, and a few fancy shapes too!)! They had some larger ones for under $5.00! Then I looked in Hobby Lobby and Michael's craft stores and found some even larger bases in their bare wood section. For between $1.00 and about $20.00 you can find some VERY NICE wooden bases already routed along the edges and in various shapes and sizes! All you need is some stain and varnish and you have a ready made base!
Quick and easy bases if you don't have access to woodworking tools, like me.