Order taking & invoice generation app for 3DCart ecommmerce store

I have online ecommerce stores hosted on 3DCart (ASP/ASP.Net based). I would like an app that's usable on both the iPhone and iPad. The app is to pull out all product information from the ecommerce store and store offline temporarily (days). It will then let the user compose an order by selecting category, products, options and quantity. The user can also search the product name and description or options. The order, once confirmed, will then have the customer information entered. Once the order is committed (confirmed and have customer information stored) can then be formatted into an invoice in pdf format. The user can choose to email this invoice *both tO, cc: & bcc:). The user can send an invoice summary containing the list of all customers, invoice number and total amount payable. The user can later choose to sync the ipad's product inventory that will only update changes from the ecommerce store. The user can choose to flush the inventory from the app and retrieve anew. The user can also choose to flush the orders and invoices. More details will be in the requirements doc.