This is a beautiful machine and cabinet!
How much is your time worth? You can always lower the hourly charge by the value of the enjoyment you get from doing the refurbishment. How much will your supplies cost to buy for the refurbishment? Are you refurbishing for family or client? Is the treadwheel going to need work, too? Are you refurbishing the cabinet? Too many variables to offer an example. Check online to see how much refurbished models like this have gotten on the marketplace in the past and that will give you a realistic idea of what folks might pay to have a beautiful one in their home -- especially if it works!!.