I started out small and decided to expand with my rodents. The only way you know if you will like it is to buy a few rats and try it out. I'd suggest buying one male and one female, you'll need to separate them while the female gives birth and weans them before you put the male back in. Then you can euthanize the babies with CO2 when they are the right size and store them in the freezer until the next batch is the right size, otherwise they will grow too big for ball pythons. You can also feed a few live when they are of size, but in a few more weeks they will be too big.
With the right bedding and setup they don't smell at all. I now use a combination of aspen shavings and pine pellets, a carbon filter in the room and an Air Wick plug in filter. I change the bedding once a week, if you want zero smell you would have to change it out every four days or so. I enjoy breeding rats almost as much as I do breeding snakes. And if you can find cheap or free bedding and food they can save you a lot of money, you can even sell your extra or trade them for snakes or other supplies. I feed my rats all of my leftovers from the kitchen! They also have a constant supply of Mazuri 6F rodent diet. At one point I used shredded paper from work, the bedding was free but didn't cut down on the smell as much and it was pretty bad after four days. Aspen is much better but a lot more expensive.
If I were to start over and start small I would get one single level of an ARS rat breeding rack (ARS-5032) as well as a few extra tubs for bedding changes. It would cost you about $300. The system will water and feed the rats with zero waste. I started with aquariums and it was a lot of labor, the rack makes it so easy.
http://arscaging.com/ars5032.html