I'd say invest $100 in ball python books first. Next, call around your area & find a qualified & reputable exotics specialist/vet, & then call them directly for prices (ask for office visit plus meds for a respiratory infection & also cost of a fecal test). Attend a trade show in your area. Visit as many reptile pet stores as you can & observe how they treat their snakes on a regular basis(good & bad). Start browsing the classified ads to see what snakes appeal to you most. Make sure you are aware of the often unpredictable eating habits of balls. Be sure to know what/how your snake eats far in advance of purchasing it. Get your tank/heating/substrate/temp & humidity gauges/hides all set up & ready to put new snakey in at a moment's notice, in the very likely case that after a few weeks of classfieds, you will fall in love with *many* morphs.
Before purchasing, post on the board to check the seller's reputation. People will email you privately if they have any personal negs to share. If you have your snake shipped to you, be 100% sure that you will be home to sign for it!! All seller's require a signature. The snake does not deserve to have to spend the night at the local tansfer station in a cramped box with nothing controlling it's temps or humidity or air flow. Shipping can also be affected by the local temps at either location. If too hot or too cold, a good seller will hold off on shipping till a later date.
If you don't power feed or get a picky eater, a female will usually take 2 to 3 yrs to mature to a safe breeding weight-(minimum of 1500+g).
Once you know what/how often your snake eats, you need to budget for the cost of its food (and the other stuff while you're at it-including the future incubator cost).
Personally, for your first female, I'd get at least a 2006.
Of course there is an entire spectrum of debate on "to breed or not to breed." Be sure to carefully review the breeding sections of your snake books & post ?s here.
Now that you got bit by the bug, enjoy the ride!! 
If you ever stop having fun with this hobby, that's how you'll know it's time to get out.
