App store rules state “ You must not directly or indirectly target iOS users to use a purchasing method other than in-app purchase, and your general communications about other purchasing methods must not discourage use of in-app purchase.”

I’m pretty sure that means you’re not allowed to let the user know in any way, even on your site, that they can get a better deal than the IAP.

Besides, apple clearly intends to get a cut of hey’s business. If they find a loophole, it will be closed soon enough.