My friend owns a pet store nearby, and she has some herps. She is mainly into fish. I can tell you, she started very small; sold feeders, crickets.. She had the advantage of having family that owned retail space; otherwise, rent and utilities could eat up a lot of your money..
I can say that if you are starting any biz, you should partner up with someone that has a concrete income that can support you in your venture. My fiancee has a property management biz, and there were a few months that my 9-5 job supported us fully; other months, he carries us by.