Wordpress updating calculations

I want to add a pricelist to a Wordpress page in such a way that the user can change quantities of various items and see the total cost adjust immediately. The attached spreadsheet shows how quantities are selected from a predefined list and prices are reflected. The format should be pretty much similar to this, with quantities, description and total price on one line. You may use an existing widget or plugin, but please include its cost (if any) in your bid. You won't be given access to edit my website, so the deliverable should be in a form where I can see it work, and can copy it in to my own website easily. The format must allow me to change prices and add/delete items, though a special interface for that is not necessary - if I have to change code that is ok.