Price per Unit

You can allow users to list by a unit of measurement instead of quantity. You may want to allow a listing by acre or mile. To edit this go to Admin Dash > Manage> Service Types> Edit and scroll down to Enable Per Unit Pricing

 Check the Enable per Unit Pricing option and then also ensure that the Schedule Booking is turned on under Calendar. You may also want to turn off the hourly, daily, etc. pricing options.

Once this is turned on you will see the  Number of Units tag show up on the new listing page. 

Additional Note

You can change the text  Number of Units by editing the translation key  reservations.booking_module.number_of_units