Whatever he or she wants to charge!
There is NO cap on the price a locksmith can charge a customer to open a Car, open a Home, Make keys, etc.
As a locksmith for over 13 yrs now in the Portland, Oregon area. I have seen licensed and unLicensed Locksmiths charge whatever they want.
The locksmith will tell lies to the customer and mark up their prices and the customer does not know what is true and what is not.