"yeah maybe a couple grand"
That's still a lot of money.
I think that enough people will want a white snake that it will take longer than you seem to think for leucistics to reach even a moderately affordable level.
I guess it would depend on how much you paid for your hets and how good a job you did of breeding them but I think even the worst case scenario can make a profit.
Suppose you buy a male lesser platy for $50,000 today. If you take your time growing him up and only breed him to two females for 2006 you might get 3.3 lesser. Maybe you sell the males for $5,000 each so only have $35,000 to make back before a glimpse of a profit. Now if those females take there time growing up maybe in 2009 they produce a total of 18 eggs and lets say 4 leucistics bred back to a platy. If leucies are still even $9,000 each you have reached the profit zone in 5 years. You have the next 20 years to bring up your rate of return.
Of course if I had a $50,000 snake I would try to breed him sooner and to more females. Also I would try to get the best deal I could on an entry snake which is a bit of a moot point as I don't have $7K for a mojave male (if they are really available for that) much less $50K for a lesser platy male (also technically not proven to some people's standards).