I had Epsilon plate made out of 1.5mm acrylic, so it was pretty cheap.
I found that a single plate by itself isn't very sturdy, and I broke it twice putting in switches and stabilizers. However once it was together, the cracks didn't make any difference at all. The final assembly was plenty sturdy because the connections and the pcb add lots of rigidity. Once I started typing I found that the give of the flexible acrylic made it the best-feeling board that I have.