Epoxy and plywood tank vs stock tanks?

I was wondering if anyone has ever done a cost comparison between building your own plywood tank using epoxy to seal it and stock tanks. One thing the plywood has going for it is variable shape. You also can have a glass or acrylic window in a plywood tank. You can find info and step by step instructions on building plywood tanks up to 500 gallons at http://www.garf.org, in their how-to pages section. It sounds like a lot of people are using stock tanks, but I thought I’d through this out there I’m looking forward to receiving by first DBT, arriving saturday – Thanks Julie! Adam Ritchie Barrie, ON http://anraviary.cjb.net