I too, prefer computer models.
But if you really want a cheap set, just go to the local craft store and by a giant bag of small, various colored Styrofoam balls. Toothpicks then work great for single rigid bonds, and you can use paper clips for double/triple bonds (you can bend them to the shape you need! or anything else rigid but slightly flexible).
This is of course just a simple ball and stick model, but you can make your carbon atom d2sp3 hybridized if you so chose...if you like making up crap.
I am not sure when I got these, or why, but some how I managed to get 2 free sets of this:
http://www.amazon.com/Prentice-Molecular-Model-Organic-Chemistry/dp/0205081363Not that I ever really use em, ehh.