In continuation of the spirit of this thread, I've finished my DIY stand for my cheap second hand tank. It's a 66 gallon 'picture frame' aquarium. It's about 3' long by 3' deep by 15" wide. I made the stand using about $25 of lumber and a dozen carriage bolts I had laying around. It's about 1' longer than it needs to be to make room for food tanks.
The filter is a sump consisting of three 5 gallon buckets. The main tank will drain with an overflow box (that I also got second hand), and I'll drill the smaller food tanks to plumb everything together. The protein skimmer isn't finished yet. I estimate the materials so far at around $75, not including the pump. The glass tank was $60. The overflow box was $20. I bought two buckets of instant ocean on ebay for