Is it possible for me to offer a discount to the published price ? Essentially I want to allow somone to enter a promotional code, that they would have received via email, when they are purchasing my App. If standard price is say 9.99, if they enter the promo code, i want to charge them 50% of 9.99. And, on their invoice, show full price, discount and final price. Is this possible ?
Discounting an App
No, there is no way to do that. You can gift it to them (making it totally free to them), or send them a promo code which would also make it free to them, but apps obtained using promo codes can't be reviewed on the App Store.
>if they enter the promo code, i want to charge them 50% of 9.99.
You may have just described how the edu discount works...sans invoice, of course.
But as noted, the app store doesn't offer the exact scheme you seem to have in mind.