Cost is something that varies a lot. Home Depot and Lowes both offer key cutting. Use the following as guidance to max pricing for key cutting.
If you have to purchase a new lock cylinder / switch and keys- try to do business with a reputable supplier of good parts that keeps an inventory -- many parts sellers have to order the part from a wholesaler after you order, then they ship to you after they get it.
The only currently authorized parts seller on the forum is someone that fits that. John Dikov @ valley scooter parts current shows those kits from $25 to $50 depending on which you need.
http://scootdawg.net/forumdisplay.php?f=59