Looking for around a 20'ish gal tank - non tempered

[biggredd]

I am thinking about doing a seahorse tank on a budget (at least to get it started). I will build my own stand. I have a 15 gallon tank I will use for a sump. I plan to use a maxijet 1200 as my return pump since I've heard the horses don't like tons of flow. I figure without about a 2or 3 foot up travel I will still be pushing 200 gph. so if I get a 20 I'll be doing about 10x turnover approx.

So I need around a 20 gallon tank that is not tempered so I can drill it. And must be clean, no tanks that have been sitting around with a ton of grime all over it. Cheaper is better.

Thanks.