No, this is how stores work. Wal-Mart will also not stock your game if you are selling it for half MSRP on your website.
What do I mean by that? Gatekeeper.
Yes they can and do regularly. The extreme example is of course an exclusive contract where the vendor agrees to make it impossible to buy the good elsewhere.
Apple, on the other hand, is imposing restrictions on which price you must sell it to third parties, and, that, I think, is illegal.