I just found a good deal too, but mine was on a new tank! I've been searching everywhere the last 3 weeks for a 6'x2'x2' tank second hand but havent been able to find anything. So I started getting quotes to have one made new. In the end I got a quote for a 6x2x2, 10mm glass, drilled with corner overflow for AU$380
Most quotes I got for the same were around $500, I also just picked up 2 x 150W Metal Halide downlights with globes for AU$30 each!
My job for the next couple of weeks is to build a stand and hood for the MH lights