You guys have so many great suggestions! I had wondered about the interlocking pieces from the hardware stores and the kids blocks also. They do look like the ones from KnitPicks. I will check those out next time I'm in town.
I like the idea of the "tig" rods. That seems like it would be much more economical than the lace blocking stuff I've seen.
I'm working on the fronts of my sweater, so I don't need this immediately, but I want to buy them in the next couple of weeks, so I'm all ready when my sweater is done.
Thanks for all of the great ideas!