Steve Osborne (Professional Breeders) used to have a pretty good article that he authored on his website, talking about how to choose species to work with. I don't know if it is still there but I would take a look. I thought he made some good points that can help you make half a decision. The first half, I think you have to like what you're working with. The second half is the economic one, how/when/if you'll make money.
I would love to be able to breed elapsoides, temporalis, thayeri and alterna- stuff like that, but I don't do well with small or fussy snakes (learned from experience). So I admire from across the vendor's table, hahaha.
daveb
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in the light, you will find the road...