What is a "list price" for an airliner? Such a thing doesn't exist anymore, though years ago it used to.
Manufacturers have a manufacturing cost for the aircraft a customer orders, but every customer is different.
The manufacturer will have a base price for a "standard" airframe but this won't include the final avionics, cabin, galley fit and it will vary depending on if an engine choice is offered.
What the sales team arm themselves with are normally figures for a basic airframe plus engine options and some guidelines for additional costs for the aircraft to be finished to delivery condition.
They then listen to the airline's requirement and go away and get the estimating department to quote a finished figure.
Then the negotiations start based on numbers required, delivery positin and all the items the airline wants included/excluded.