I used to work within sourcing in the telecom industry and I know for a fact that different prices for different customers are common practice. The bigger you are the more bargaining power you have etc. I very much doubt that it is illegal. I would however imagine that Apple would have at least two suppliers of their LCD in order to not be trapped in an agreement etc. I also very much doubt that Apple will start making their own components since that is a completely different industry. You have to remember that Apple and most of the companies in the telecom industry are almost entirely relying on outsourced production, I don't even think they have any production on their own and are relaying on Foxconn for that.