Forms entered into shopping cart..

I have a complex order form I have designed using formspring for customers to purchase custom built radiator covers. It works great for what I need it to do and formspring makes creating and editing the form extremely simple. I am looking for a shopping cart solution which will allow me to input the created items information using a url redirect. The price of the product is the most important, but I would also like to have a description formed using the information in the form as well, mainly for the customers reassurance. I have the forms ready to go, but can only have one order per transaction through paypal without a shopping cart to manage the items the way it's currently working. I also need all of the normal funtionality of most shopping carts available such as, a stored customer database, the ability to give retailers a percentage off their total as well as a line of credit, be able to run coupon promotions and also provide multiple fixed price items on top of the custom order ones. I have been searching high and low, reading up on a multitude of shopping cart programs and have not been able to find a solution for importing the form info to the cart to form a customized product. The order form has a lot of dependencies that ultimately form a figure which is multiplied by the sum of the products given dimensions.... with other values added for different options. A little too complex for any of the carts built-in ordering options I would imagine.

Any help or suggestions would be greatly appreciated!

cs-cart has a very nice product options system that will allow you to customize various options. Why not give it a test drive.