Index Card Storage?

Has anyone found a good, relatively cheap index card file? I use the little plastic boxes but would ideally like to get something with more ample room for my growing index card reference collection.

I've hung around on ebay for ages, looking for old library card catalogues. But these get pretty expensive, and many of them are for pick-up only. They can also be pretty dingy.

I would love a simple, new index card file (especially one made of wood). The ideal would be a single drawer unit with the possibility of buying additional units. Any ideas? Maybe I'm not looking in the right places...