Somehow I am on the mailing list of a petroleum equipment supplier (www.jmesales.com). Check out the vertical storage tanks, made of a material referred to as "Dura-Life", but not specified. I'm guessing it's some type of fuel safe plastic, the catalog doesn't say.
Small diameter but tall and stable, with a see through type sight gauge, molded in tie downs, vented fill lid, and of course an outlet fitting. 500 gallons for $551.00, seems like a pretty good deal for a brand new tank in a here to fore hard to find type size, meaning tall and skinny. I have a 300 gallon steel fuel oil tank, one of those oval types, I got it free (less then a 2 years old, the home owner switched to propane, and I did the crane work to set the new 1000 gallon propane tank, and offered to haul off the "old" tank for free), but one of these vertical tanks (secured of course) would have fit my hangar ramp better, as the scratches on my wingtip will attest!
The thing I really like about bulk fuel purchases/storage, is you only get pissed once, when you pay for it, then for hopefully a fairly long time afterwards, it's "free" fuel. Not to mention it makes the record keeping easier if you burn mgas, and file for the road tax refund at the end of the year.