I have seen some excellent resin ones, but now I can\'t find them. Perhaps when Shawn comes on he\'ll know more (our resident terrain expert).
I found some nice paper ones, you can download the file and print them out. With a little glueing you can bang out as many as you need, but I don\'t know if you need them more durable for a longer campaign.
THE LINK
And if you like this sort of thing, here is
another site that has an incredible assortment of terrain, vehicles, and buildings that you create using your printer!