Convert customer inquiry to order

Is there a way for the vendor to convert an inquiry from a customer into a purchase? Here is my use case:
– Customer sees product they are interested in, sends inquiry to vendor
– Vendor receives inquiry and responds. Often the vendor may need to customize the product or price and explain choices and changes to customer in the reply.
– Once customer agrees to purchase, the vendor converts that inquiry into a purchase.

It is almost like a configurable product, but there are too many variations to actually create configurable products. I guess what I’m looking for is a way for the vendor to take that inquiry and send the customer a link to purchase a “custom product” where the customer can purchase. The vendor could actually create the product and price it accordingly, and then send the customer the url to that newly created product, but that will result in a lots of single-use custom products in the system.

Any ideas?