Switching now will be much easier. Most stubborn balls can easily be pursuaded to take rats with a little scenting (simply rub the mouse on the rat).
10 gallons is a little small for adult rats, although I keep females in 10 gallons with her babies until they start to become mobile. A 20L or even better a 55 can usually be had on CL really cheap. Again, racks work great if you're dealing with large amounts. If you're only going to keep a few balls, its cheaper and easier to just order your feeders from a breeder. Rodent Pro has always done us right, but there are lots of others to choose from that offer high quality feeders. We only deal locally (never shipped frozen feeders), otherwise we would gladly match online prices. If you do a little research there is probably a rattery close to where you live that will give you a good deal and you can forego the shipping costs.
If you need any help building a rack, hit me up and I will send you some of my own plans and some of others so you can find what works best for you. Most people here would laugh at our racks. I built most of ours when we were just starting out and they are very ghetto and were usually built from shelves we picked up at yard sales/thrift stores, but we have yet to have a single escape. Only two were built from scratch.
Butters are great. I haven't personally worked with them, but my wife and I have been discussing playing with them next year providing we find one that we like. As I said with the spiders, butters also have lots of potential. Pastels are a great co-dom to work with as well and can make some killer combos. Its really all about what you like and your willingness to experiment.