How many rats i enough?

I moved and now I cant get any rats so I bought 2.9 rats to breed. But I'm wondering how many rats I would need to give my 10 adult ball pythons food every week?
I only feed small rats, and If I produce more rats than I need theres no problem selling them to pet stores.

Here is some pics of the setup, tryed to keep it as simple as possible

http://i222.photobucket.com/albums/d...s/DSC00133.jpg
http://i222.photobucket.com/albums/d...s/DSC00134.jpg

And lock at Harry Potter here, so sute!
http://i222.photobucket.com/albums/d...s/DSC00136.jpg

A good rule of thumb is 1 female rat per snake. For 10 snakes, I would just use 12 females and have a litter a week.

Rotate the females through the males tub like so

3 weeks with male; pull her after 3rd week
1 week alone; she will give birth mid week to pinks
3 weeks nursing; I pull the rats at 3 1/2 weeks (saturday)
4 weeks of rest

start over

This should give you roughly a litter a week, unless they are late at getting pregnant, or too young/old/feisty.