When it comes to bookable Products or Services such as Holiday Rentals, Boat Trips, Bicycle / Quad Bike Rentals and so on, you have multiple choices how to implement it.

1 You could just add a normal Inquiry Form where the Customer can leave all their Details and Requirements such as Dates, Nr of Guest etc. This will be emailed to you and you can then take up further contact to arrange payment or part payment (deposit) for the Booking. Examples of free customizable Contact Forms are:
Contact Form 7 
WPForms 
Forminator Forms 
Fluent Forms
And many others.

2 You could make use of or engage a third party payment processor. This usually involves having the Booking Inquiry Form on your own website and then link the PAY NOW Button to the third party payment processor. They usually charge a small commission for each sale (or have an annual type of Membership Fee). This will probably be still cheaper than than any of the OTA’s Commission you would have to pay there.Examples of Payment Processors are:
PAYCLY 
Easybookings
Webreserv 
And many others.

3 You could invest in your own Booking Plugin (if its a WordPress Website). Booking AND Payments are done on your own Website. Various Booking Plugins exist. Some charge an annual Fee per Site, some a percentage of the Booking Fee and some a once off Purchase Fee.
Booking Calendar 
WP Travel Engine 
WP Booking System
Motopress Hotel Booking System 
And many more.
If you need help implementing any of the above solutions please contact me. Advice is free