$100 per snake per year.....thats how I have been figuring new snakes into my cost estimates. It is really hard to figure in exact number on feeders because when bulk frozen rodents are purchased, the price generally varies with the number purchased. If you have a place to store a year's supply of frozen rodents go for it and you will save a few dollars in the long run. A ball pythons eating habits can also effect the estimate ...if one goes off feed for a few months not as many rodents will be need.....and also there are unexpected costs like....vet bills.