I've got a 55, 40b, and 29.
I'll stop when my floor falls through.
Lol, I'm not sure why tanks are so addicting because they are so expensive. I have the same bug though! Two 10 gallons, a 65, a 60 and two 20 gallons. It's crazy, because I still want more.
If it weren't for me living in a studio, I'd have more than just a 10 gallon and 5 gallon (hasn't been setup yet) tank.