Ball pythons also were just one of the first snakes where morphs were found, starting with the albino. Another popular morph snake is the corn snakes. Some of the larger snakes are just harder to handle and breed. Boa's give live birth, are larger in size, and cost more to care for in larger quantities.
If you want to see some awesome morphs and other cools snakes check out snakebytes.
www.snakebytes.tv
Click the 'all episodes' button and start from the bottom or pick and choose which ones you want to watch. Brian is great and covers a lot of subjects in these you tube episodes.