It's not a crime to actually make a profit breeding ball pythons, not sure why people always jump and say they are not in the hobby to make money. In my opinion you should be thinking about both your favorite combos and what will bring in some money to at least cover your time and feed costs or at least break even so you can really enjoy your hobby without breaking the bank. You could breed to a pied but your offspring will be all het pied, only a few possibilities with that, and you'll have to wait about five or six years to actually produce a pied if you decide to breed back the het pieds. Although the het pieds may increase the price of your babies.
Personally I'd probably get a three gene combo to breed with him. What is your budget? Here's one sub $400 with three additional genes that you don't have. That would give you six genes in your breeding program with some nice bright yellow colors and you could possibly get a five or six gene snake out of the deal:
PASTEL / FIRE / SPIDER FEMALE
http://www.morphmarket.com/c/reptile...-pythons/22872
Here's the cross possibilities, you could breed this pair for ten years and not get all the possible combos, it would be a nice long term project with just one pair of snakes: