The absolute best clowns to start with are also the best ones to breed to make money. That would be orange ocellaris.
Percs take too long to grow and develop. Black ocellaris take too long to start breeding. There is always a market for ocellaris. LFS will buy 25 or more at a time. When was the last time you saw 25 of any clown other than ocellaris at a LFS.
Expensive clowns are not the best choice. Most are difficult to breed, more difficult to raise, and once you do, you have to sell them one by one to clownfish collectors, because very few normal people see what we see in a rare clownfish. After the excitement wears off, I don't always see it either. I was very excited about getting a white-cap clown. After a few months I started to realize that it really wasn't that pretty and had a horrible personality.