Essentially I need a Mobile Web App on the iphone meant for group purchasing. The way the program should work is that when people open the program, if enough fellow iphone users purchase from the participating retailer they get a percentage off of the total price. I would like the concept tailored for take out restaurants, online retailers and fast food joints.

They should be able to pay and check out their item through the iphone using credit cards, paypal or google check out. The user should be able to chose their retailer, chose the deal they want to enter, see if others are already involved, wait for others to place an order until they hit their intended target and when the number is reached the total order is sent. They should also have the ability to dial out to their friends so that they can invite them into the group. The user can also cancel at any time.

The app will probably need to sync to a website with a database of retailer phone numbers, hence, the Mobile Web App. Also it should be easy for me to add or remove retailers who enter the program with their deals. So you have to show me how to update the database. That said, I would really like a professional to help me work out the wrinkles for a program that could be the iphone's next big killer app!