So, I'm looking on Craigslist and find a 100 gallon tank for $50. Unfortunately, it's one of the older slate-bottomed tanks with the stainless steel frame. I know it holds water at least halfway right now. I'm not sure if it's worth going to take a look and seeing if it holds water all the way up or not (about a 40 minute car ride). I have NO experience with this kind of tank and do not know how reliable they'd still be after all these years, nor how difficult to fix it would be if something did go wrong.