Sounds like me... I started picking up small tanks at garage sales for $5. Each child had their own tank. Then I bought a new 55 gallon in April 2007. We combined the freshwater fish from the kids tanks and put them in the 55g. By June 2007, I knew I wanted a bigger tank. I picked up a 40g (used) that summer too with a stand for $50. By November, I had saved up enough money for a new 125g. The used tanks 10g -20g have been great investment too. I have had to use them for QT or just a holding tank while I fix a leak in a used tank I picked up. Now I am thinking about using my 40g as a sump for my 125g. I don't think I will buy anymore large tanks due to space. But I do plan to convert my 55g to SW. That would leave me with a 125g and a 55g.