Will your snakes take f/t, or are they picky about live feeding? I didn't start breeding rats until I had 7 ball pythons and started flinching when the feeding bill came around. Rats are much higher maintenance than snakes, and much less forgiving of husbandry mistakes, especially when housed together! It couldn't hurt to have a colony, particularly when you have little snakes around, but just know that the rats will soon take up as much if not more of your time than the snakes.

If your prepared for all that, then by all means. You could get some young female to start with and raise them up to a proper size, which should give you some time to familiarize yourself with rat husbandry and make sure you have some quality females (it's just as important with rats as with snakes).