OK, well we can debate this to the ends of the earth. Basslover - you do have a point. a plywood 600 could be built for under 2200... probably. an acrylic 600 gallon tank is a different beast than a plywood 600 though, and I think that's what he was thinking about building. Personally, I would not touch fabricating a plexi 600 with a 10ft pole. a plywood/acrylic one though I'd be on it like stink on ****.
I think, however, if you want to build a plywood 600 that is of a similar caliber to an all acrylic, prefab 600, in terms of beauty, reliability, and the fact that it's clear all around, you might have trouble doing it on a shoestring budget. Materials are not that cheap, and if you use budget materials, you often get a budget looking tank. I also think that if you don't have 2200 to spend on your 600 gallon tank, you aren't gonna be able to heat, decorate, stock, or filter it, even if you build it for 1000.