The Sylvania one I had in my other MV tanning fixture (not posted here) went bad. I guess it was just barely hanging on. 
It needs to have a mogul base, not a medium one.

 I'd check eBay . Sometime they show up rather cheap .

I've seen them before in thrift stores like Savers. Usually still installed in the fixture.

There's a GE sun lamp with fixture & box for $15 at the local antique mall . No idea if it works though.

Yeah, some antique malls are good places to look for this sort of stuff too. I once found a new 1000w H36 Philips BT-56 lamp at a antique mall.