what are the costs/charges for using hotelbed hotel and booking apis?

Hotelbeds doesn't publicly publish their rates. As their APItude service has multiple sets of APIs and various types data that you can request, the end pricing can be very different depending on your needs.

So, the best option would be to contact Hotelbeds directly and provide them with the list of services that you plan to use.

However, you can test the APIs in the sandbox mode prior to opting for some specific services.