I have a snapping turtle, and I truly love caring for him. However there is a statement I made once that still holds true.
"My snapping turtle is the most expensive pet I have, and he was free."
Seriously, the proper housing and care for any aquatic turtle is pretty high up there. Then again, a lot of that is just in aquariums, and finding filters that can keep up (Fx5 is the best so far).
I don't have any experience with venomous yet, but eventually would like to get the proper permits. Out of all venomous, I really like the idea of working with a species of rattlesnake. They're kind of the 'OG' in terms of patriotic animals in my eyes. "Don't tread on me"
Another note, I wouldn't take local wildlife and introduce them into the pet trade. It isn't good for conservation, and isn't particularly good for the animals stress levels. If you want to breed some and introduce them into the trade following all laws and regulations, then by all means go ahead.