I would recommend ball pythons or womas, depending on how big an initial investment you want to make. Regular balls are inexpensive, small, easy to handle, and a very good representative for what is involved in breeding pythons.
Womas are more expensive to get into, but grow fast, get only a little bigger than a ball python (5' to 6' vs. 4' to 5')are extremely hardy, tolerate (actually prefer) a dry environment (balls and most other pythons do better with higher humidity), are easy to handle, are great eaters, and breed easily - the eggs can be a little more difficult than average for python eggs, but with the right setup you'll do fine.
Either of these would make for a good introduction to python breeding.
Steve Reiners
BoaMorph
www.BoaMorph.com