A little hard to tell for your purposes because I bought the fabric at such a huge discount from what it costs retail. But for the tank, 2X4s, plywood, paint, hardware and all else, under $200 each.

BTW, if you need to anchor any because of unknown ground water depth, I made devies that will allow you to do that too.

Take a ride up here and I'll help you make the first one and you can see those that are installed.