Just thought I would pass along some information on rain barrels. I picked up 2 white 55 gallon barrels for $10 each locally (ITP) from Craig's List.
Food grade in excellent condition. I haven't started my project but my first barrel will look like this one: http://www.rainbarrelsofdecatur.com/. It will allow me to get inside the barrel to install the spigot and do a yearly cleaning.
I will make the second overflow barrel a different way. the barrel will be upside down with the drain in the existing cap.
Here is another listing I found on CL. I imagine you would only need 1 and cover it with something pretty.