Waitlist not an option

I have registrations set up on a commerce product (that costs money) with a capacity of 3 and a wait list of 0 (unlimited, but also tried it at 5) and once the original 3 slots are filled, the cart button is removed and says

No slots available
This item is currently unavailable.

I'm assuming that a user should still be able to hit the cart button and submit info to get on the wait list (register with a wait list state), but there's no option for users to do so. Am I missing something? Also, if a product costs money and users need to get on the wait list, do they still have to pay the money to do so or can they bypass that just to get wait listed?

Thank you!