We had done a booking modification for one of our clients. It was a very complex project with lots of details. We would be glad to implement a booking module for your online store. Please, contact us, if you are interested. If you have any example how it should exactly work, please let us know it.
As far as I know, there isn't a ready-to-use booking module for CS-Cart and I haven't noticed any CS-Cart integration with third-party booking systems.
Best regards, Alt-team