This is one of those age old questions.
I'm not sure anyone of us have truely mastered teh delima on how to store cake supplies. It seems just when you have it all figured out you buy more and there goes your plan. It also depends on how much room you have, what supplies you have and so on.
I've done the rolling carts with drawers, bought on sale, and they worked great, but I have out grown them by buying more and more things. Right now I'm currently trying to buy enough plastic containers to be able to neatly organize my cake stuff. I'm putting like things together. Problem is no matter how many containers I buy I keep needed more.
I'm lucky enough that I have a whole room for cake stuff, so space isn't an issues, the bigger issue for me is finding a way that works best for me. Hopefully the shelves and plastic containers works out for me.
Also be sure to search the board for past posts, this topic has come up several times and there have been some good solutions in past threads on the topic.