Speaking as someone who used to administer a card-lock system of the same manufacturer as is commonly used in hotels, I can attest that bulk cards cost anywhere from a dime to several dollars, depending on where you buy them. Things get more expensive once they have special custom printing on them. The really cheap cards are less reliable (the MICR wears off) and have to be thrown out after a few months of heavy use. The expensive cards will last for years (and thus are more suitable for employee ID cards).

The new RFID cards are even more expensive.