My 2cents
I think the ink jet programs are awesome. It is a way for schools to make money for nothing. No one has to spend a dime to earn money this way. As another poster said "They pay you for your garbage". Plus it is good for the environment!
I would have no problem using these people as long as the pay out price was equal or better then what you would get using another company.
I don't believe they should have to forgo their profit either. As another poster said " why would you let an outsider make money but not them?"
As for other parents having the same business, it is highly unlikely in this area and if by chance it did happen. The answer would simply be that they asked first and unless they were going to offer you a better deal then you had no reason to break your agreement with the other person.
However, I would not let these people chair this program. Chairing this program is very easy as it is very little work. But in order for checks and balances to exist I would get another person to chair it.
I agree that Avon, Tupperware, and the like are very different things and of course you can have any number of parents involved in these businesses. Those I would stay away from