That's cool, do you have someone ready to buy them? If you're planning to sell them to a LFS, you may want to check with that LFS before you begin the breeding process. Many LFS's won't "buy" fish from customers anymore, and many won't even take excess from customers due to lack of space. With guppys you might have a chance at getting something for them, but if you're planning to profit... don't. The standard markup on fish in a LFS is about 60%. Look at the prices they sell for, deduct that 60%, and figure that is close to the wholesale cost... and LFS's won't pay wholesale prices to customers, there's not enough profit involved.
Good Luck with it!