They even tell me their snakes can tell the difference and many will only eat my animals and will fast if offered rodents from another source. My snakes are the same way. Once or twice in the last few months I've had to buy a few feeders when my stock was low, but I learned the hard way my snakes won't touch feeders from someone else. I ended up making breeding stock of a few feeders I bought, and having to give away the rest.
That's crazy. Is it to the point where you feel responsible to warn customers interested in your snakes that they may need to buy their feeders from you as well?