391551 Calculating Fields Order Form

I am designing a page in Dreamweaver that has multiple products with descriptions and options for each. I need to have a form that lets the user add products they want to buy, calculates the quantities, collects basics like name, address, etc. and sends the form via email. Not sure if it's best to allow products to be added as you go, taking you to a "checkout" like page, or just a single page form. Please let me know what you suggest. Basically, we want what would be a purchase order idea, sending the order, but the user doesn't have to pay yet. Once the order is received by us, we would send an invoice (via PayPal for now). Eventually, in the next stage of development, we want to make it so the user would set up an account to check on the order status and order history. So with that in mind, maybe this form would develop into that. So I want to provide an html page that would be taken by you then coded and tested to make sure it's working.