Vikki, it sounds to me like you want some sort of shelving unit to hold the cages you have now, correct? I like Nanci's idea of using a book case, or you could build shelves. Maybe IKEA would have something cheap that either matched what you have now or was easy to paint so it matched.
The only thing I worry about is getting in and out of the cages. I imagine that the next shelf will be relatively close to the top of the cage, which could be a problem for accessing the cage. You'd have to remove the cage to do so, or have some sort of sliding mechanism...