Quite simply: Keep dreaming. Apple (or Google) will not distribute an app that is used for adult purposes or sells adult materials.
It could be done as a third party app for Android, but the logistics of coding it to match the relatively innumerable specs of different phones/tablets isn't worth doing (because I don't see anyone PAYING for an app to then go shopping with)
My opinion: An app would be spec-fucking-tacular. It won't be happening any time soon though!