This is the order I'd set things up:

Rack System First, if you want to breed and want something simple I would say get something to allow 1 40+q per level for each female you want (IMO go with how many you want +1 for another just in case) then 2 32q per level for however many males you want (again +1 level IMO) then you will want hatchling levels (should be able to fit 12q tubs 4/level and you will probably want at least 1~2 levels per breeding female you have). Either build it yourself or buy some racks (if you buy I would say get your female rack first, probably a 3 level, male/juvenile rack second, and then third your hatchling rack when you are about to breed). When you get this you will want a thermostat.
After you have your rack setup get all your temperatures figured out you will need a temp gun, a scale, some hemostats, hides, water bowls, substrate, and you may want a miniature freezer for storing rodents.
Then you should go out and get your females. You should figure breeding after at least 18 months of their life and 1500g or more. Get your males a bit before breeding (6 months or so) and then get them up to 500g or more.

Before actually breeding make sure you can build an incubator, you have your hatchling rack and you know what you are getting into. THEN you can breed.

Figure your first rack will be between 200 and 500 dollars building or buying, building would be cheapest but you will need the space to build it as well as air it out if you put any sealants on it. Then figure around 200 extra for the little things (scale, hemostats, hides, bowls, etc). After that you can start thinking about your snakes, which depends on the snakes you are getting for price.

And don't bother breeding rats, it actually costs you more than feeding frozen. You will need quite a few snakes and quite a lot of room before you should breed rats.