The sheet it got from a scrap yard who has no market for titanium so I end up getting it for "almost free". Some of it is in good shape but a lot of it is pretty beat up. I didn't think there would be much market for unknown alloy, dirty, beat up and ground down titanium. I had some pieces the right size kicking around so I thought I'd give it a try. I would definately be up for some trading for some of the stuff in better shape though. Suprisingly enough i haven't had a problem with it warping, I used it as a cover for my furnace I use for casting. The center of the sheet will be bright yellow and the corners not even glowing and seems to be pretty stable. I'll watch it closer but it wasn't noticeable if it did.
Thanks for all the replies, it pretty amazing to hear from people so quick.
Drq