there are alot of factors, do you want a downdraft? do you want one with a furnace or bake lights or both?
i am actually building my own out of insulated tin walls, and buying all the lights and heaters and fans etc etc etc, but he can look to spend alot of money depending on how often he will use it can change what he needs greatly! but for one ready to put up it can be a mid range price of about $15,000
but some people might be going out of business and will let one go cheaper
good luck