I want a bigger sump

[tinpusher]

I have more room under my tank and I want as big of a sump as possible. I am looking for a tank as close to the maximum dimensions of 57"L x 17"W x 16"H as possible. Where can I get such a beast? Or better question where is the cheapest place to find such a tank? I will put WTB ad in buy/sell forum but won't hold my breath as I am thinking custom job.