Gary, I heard that Petco or Petsmart is having their dollar per gallon sale. I don't know if it's true but you should investigate and go pick up a 20L.
I have one with two holes drilled up high in the back. One has a crack from the hole to the corner, but when I had water in it, it didn't leak....probably because somebody put some black rubber background on it...like a paint on stuff. I hate to throw it away, but if you want to use it for a sump, it's free.