Go to Fauna and Kingsnake. Look at the listings of each of the animals you're interested in breeding. Look for availablity and price. This may give you some insight. As much as I love Dums, I don't see much of a market for these guys right now. But this is in my area, others could have buyers before they're born. It's kinda hard to tell you what to do since I'm on the other side of the US.

Good Luck!
Jim Smith