The thing about the yellow bellied balls is that there is rumored to be a co-dominant ball python where ONE of the traits of the hets is that they have yellow bellys. Allegedly, those particular yellow bellys produce a homozygous form resulting in the ivory balls that the snakekeeper is producing (although I have not actually seen anything in print from the Sutherlands confirming this). This rumor seems to have given license to every hack in the buisness to comb through their copious stores of imported animals searching for anything with a yellow belly and selling it for an insanely high price. Now, before I hear all the whiners telling me that they can sell their animals for any price that they want to, I say that I agree with them. You can sell any animal for any price that you choose and let the buyer beware.
If I wanted to I could go door to door selling pencils for 20 bucks each too. If I'm a good enough salesman and can make those pencils sound like something really grand and make you believe that you can write a million dollar best seller with these pencils I'll probably sell quite a few. It doesn't detract from the fact that they're just pencils. You just paid a lot more for them then you needed to.
Likewise with ball pythons. I don't believe that most imported (unproven) BP's are worth more then about $30-50 bucks (on the high end) with REALLY nice ones worth about $150-$200 (maybe) The REALLY exceptional ones coming out of Africa go straight to the major breeders for many thousands of dollars and wouldn't be appearing here in the classifieds.
In my opinion, anyone selling a few imported animals for a couple of thousand bucks based on a trait like having a yellowish colored belly is trying to take advantage of you and I would caution you to steer clear of any deal like that.
VOT