Build a Quote Engine Based on External Data

In short, I'm looking for someone to create a visually appealing and easy-to-use webpage(s) for my site where customers can enter the names of products they'd like on as many individual lines as needed, then the page draws data about the items entered from an external database and also an external website to calculate a total quote for their order, at which point the customer can either modify the order or pay the quoted price- with credit cards and PayPal being the given payment options. For more detail, I'll give a walkthrough of what I want the customer's experience to entail, from step one: When they first see the ordering screen, I want there to be at least one blank line for them to enter the name of a card (a trading card game is what I'll be dealing with), with the option to add more lines as needed. When they enter a card's name, I need for it to ask which set they'd prefer the card to be from (some cards in the game were printed in several sets that were released), if any, based on an offline database I have which includes information regarding every set ever printed and the cards in each. I also need for it to ask them if they'd like foil versions of the card, but only if foil versions of the card were actually printed and available. I then need for the page to quote a price for that card using information from [login to view URL] (the widely accepted authority for average prices on these cards) based on either A) the median price of the card from the specific set they chose as preference and whether it's foil or not, or B) the cheapest median price of the card among all available sets/foils if the customer indicates that they have no preference. As the customer enters multiple cards, I need for the page to display a cumulative total price in addition to the prices for each individual card as described above. I don't think this part will be very difficult. When the customer is finished entering cards, if they are happy with the order, then this is the point where they need to be able to click a "next" or "checkout" button, submit the order and their shipping information, then pay for it. If they are not happy, however, the order needs to remain completely interactive, giving them the ability to add and/or remove cards, without starting from scratch, until they are satisfied and prepared to pay. Once the customer's order is placed, I need for an automated email to be sent to them with the information regarding their order and receipt of payment, then I need another automated email sent to me with their order in the form of a packing slip so that I can ship their cards correctly.