by Jim » Mon Feb 04, 2013 8:01 am
You can us the Variable price product option. When using the variable price product the normal price field value become the minimum acceptable value for the product On the store page the price field would be an input field that the shopper can use to put what they are willing to pay for the item. Since the price is not displayed they don't know what your minimum is set to but it they enter an amount that is greater than the minimum price you set for the product they would be allowed to complete the purchase. If the value is to low they will receive a message in the cart that the value is to low and to enter a different amount.
As for doing it the way you are thinking you would need to create a separate page for each product with the product informaton on it, since there isn't an easy way to pass the product info to an existing html page. That page would need to have the product name, description already filled in in the formmail form and a field where they could enter the price they are willing to pay. Once they submitted a price and you accepted it you would still need a way to collect the money for it so in that case you could use a Variable Price product where the name, price and sku are all variable and have a page you drect the shopper to that has this layout for a product. They could then enter the product name, sku and price you agree on and submit the form. There is a product template called invoice.sst that has this layout defined.
EDIT. For the last option you would need to create a link from your normal product page to the one containing the formmail form it could be a simple href to the page since no info is being passed, something like <a> href="http://mydomain.com/productx_form.html">Make offer</a>