Here are steps you can use to build your own 3D glasses (it boils down to "colour clear plastic with red and blue sharpie"), or buy a box of cereal advertising 3D glasses in return for 3 UPCs (or fair facsimiles), then load up the intertubes, find an address you might be interested in (I suggest the art intervention viewable here, and information about it here), then get your freak on!
We had to experiment quite a bit with the colours. The blue lens had to be almost dark teal, and the red really had to be orangey-red, not pinky-red. We only had limited success, to be honest, but it was fun trying. And that's what really counts, doesn't it?
Here's an image to try it out on: