Well unless the person is also giving you all the racks, thermostats, tubs, heating elements, incubators, rat racks, rat breeding colonies, rat food, bedding along with the snakes, you will probably not break even, heck you'll in in the hole a few thousand for a while before you start producing babies. Then you will have to have people lined up to sell your babies to.
Keep in mind only a few shipping companies will let you ship live animals, even then NONE OF THEM offer insurance. Also the market is growing, but so are people doing exactly what your doing.
I don't want to be a downer, but I've seen this happen way too much, people get in over their head and realize it's not a good way to make any money. 95% of people never even break even on their snakes when they thought they could make thousands.