Well I got some 1" acrylic priced, and for 2 4x8 sheets it is 728.00 a piece. That's is expensive to me but really even after I buy them and all the wood I ain't tallied it all up. Honestly tho if I was to have a solid acrylic tank built from a company that was 16' × 3' × 3' don't you think it would be double the expenses vice verse a plywood tank? It would have to be alot more cheaper to take the diy route I would think.
It will be even more expensive, because 1" won't be thick enough if using acrylic. 1" would be glass, which is significantly stronger. You'd be looking at at least 1.5" thick, Some of the calculators that work for acrylic won't go past 30" high.