I need help!!

My freaking 55 gallon tank sprung a leak and i have no idea what to replace it with!
i patched the hole with duck tape for now and it seemed to stop leaking!

What the heck should i get for a tank now? i heard about kiddie pools, but will these sprout leaks to? whats a permanent(CHEAP) solution?

Here is my system now! MY Rooftop System (Photo Journal!! )

I'm hoping i wont have to move anything to accommodate the tank!

Thanks!