What were your biggest purchase mistakes?

[zum14]

I bought a tank off kijiji. Fine right? Yaaa, pics looked good said id take it. Normally not a big deal, except this one was in kamloops. 5hrs away from my place. Got there. Looked at it, was super scratched. Terrible. Tanks sitting in my yard. Basically a sump now is all its good for. I did manage to get the price down simply because it was soo bad. Second time i tried this, was going to edm anyways so figured id snatch this good deal up and move into that one..... Advertised as a 120gal, got there, yaaa 90gal. Not as scratched but soon found out when doing the overflow that one side of the tank was laminated glass. Come on.... So needless to say i dont think i will be buying anymore used tanks (certain circumstances of course will demand leniency to this but rare none the less)