The Sutherlands (
www.ballpython.com ) sell a breeding balls video. It is helpfull.
Now, most of what I am going to tell you is info I have gathered, not expeireince as I have not actually bred any of my balls yet~
Female should be around 1500 grams. Male as soon as he makes sperm plugs. As low as 700-800 grams sometimes.
I would invest in a breeder rack rather than 6 tanks. You will get 6 enclosures in a MUCH more space efficient rack, ~ heat and humidity will be easier to maintain.
I keep mine seperate, as I have been told many times this is best. I have a male living with a female right now though (Wishing he was interested in breeding~ he is 700 grams and I guess just not interested yet) and they do fine.....I seperate for feeding, and I will seperate them when I see the female ovulate or I give up on this season~ whichever comes first!
Pricing depends on the time of year and quality of the BPs. You can usually get WCs reasonably cheap, but adult CBB Females will cost you a pretty penny. Less this summer than right now. If I were you I would look into CH (Captive Hatch) or CB (Captive Born) or CBB (Captive Born and Bred) yearlings (03's). You will get these for reasonable prices~ $75 to $130 depending on size) and they will be ready in a year or two. Your baby males should be ready by the time any yearling females you purchase are.
Good Luck