Yellow Belly??

So I was recently to a reptile expo in Manchester, and there were some ball pythons that were labeled yellow belly ball pythons. These looked exactly like my regular ball python, and they were cheaper( or pretty much the same price)than a regular. Is a yellow belly a type of morph, or is it just another name for a normal?

It is a morph... A subtle one

http://www.jkobylkareptiles.com/snake_room.php?id=19

For some reason around my area yellowbellies have gone down in price. It is sad too because they are one of my favorite morphs. I know a few breeders that aren't selling their females because the price has dropped so far on them.