ideas for a cool bathtub?

My upstairs guest bathroom to be has been designed for a typical tub/shower combo situation, but I want to use something interesting for the tub rather than a typical white fiberglass or cast iron built in tub.
I REALLY love this thing: http://www.designandcoonline.com/cgi-bin/category.cgi?item=Z10058type=store
and assuming I could figure out a way to connect it to a drain, I think it would acutally work but it's more expensive that I'd like and would be a pretty costly experiment if it didn't work out.
I think the only thing that would be a definite no go would be cast concrete...the floor system will be commercial type open web steel trusses with corrugated steel decking and concrete, engineered for 50psf.
I want something roughly bathtub shaped but the material could be anything durable and reasonably easy to maintain and the cheaper the better.
Ideas?

Did you read the posts about agricultural feed troughs? Where was that? Well, here is a vendor link:

http://www.behlencountry.com/asp/catalog.asp?Product=Galvanized%20Round%20EndFamily=Water%20Tanks

You did say the cheaper the better?

My upstairs guest bathroom to be has been designed for a typical tub/shower combo situation, but I want to use something interesting for the tub rather than a typical white fiberglass or cast iron built in tub.
I REALLY love this thing: http://www.designandcoonline.com/cgi-bin/category.cgi?item=Z10058type=store
and assuming I could figure out a way to connect it to a drain, I think it would acutally work but it's more expensive that I'd like and would be a pretty costly experiment if it didn't work out.
I think the only thing that would be a definite no go would be cast concrete...the floor system will be commercial type open web steel trusses with corrugated steel decking and concrete, engineered for 50psf.
I want something roughly bathtub shaped but the material could be anything durable and reasonably easy to maintain and the cheaper the better.
Ideas?