you can get acrylic from usplastic.com.
I am unsure of how hard it is to make one though. I thought of making a tank myself a few months ago, but canned the idea. My experience with pinching pennies is this. Every time I tried I ended up with a heap of $*#@! and wished I would have just spent the money. Not only that but a bad leak can make your apartment/dorm/house/parents house really messed up, as well as costing you more money than just buying one in the first place and thouroughly pissing off the people below you if you are above second floor. You can buy very large Rubbermaid containers up to 150 gal for pretty cheap. If you must have an acrylic tank try some of the online/mailorder suppliers. Many of them will custom make one for you to your specs, predrilled, overflows, baffles, etc.
