Hi I was hoping somebody might have some suggestion for some potential shopping carts I could check into. Basically I have a printing company that I am doing a store for and I need a cart that can possibly dynamically calculate prices. I need it to do either:

1) Extrapolate prices - lets say I put in prices for 1000, 2500, 5000, 10000 business cards. If the customer enters 4000, the software will prorate the pricing between 2500 and 5000 to find out the prices. As well, there may be options (select box) and additional costs may needed to be added to the above base prices (by way of forumula or something).

2) Mini estimating program - pricing is calculated from scratch based on some set parameters and can compute and price for any given quantity. I know this could be done by coding but I was wondering if there was some kind of existing cart that might work.

Thanks