Booking calendar + shoppingcart: Consulting ??
You can submit a request here https://www.interactivetools.com/support/request/ with your project details and someone will get back to you. I don't believe I have personally seen any type of Booking calendar plugin existing yet.
- Booking system and room occupancy for a couple of backpacker hostels (no payments) ,
- Event Booking system with Simple Cart payments,
- Complete fractional/shared ownership resort management system with member date allocations, time-swapping etc no payments.
Greg@Itools has done the majority of those with me