This is handled on the Rental Quote Plan (CQP).
Or one can manually create a price a price agreement (PRA) when the order is created.
Each order you make will have its own price agreement (PRA) which is a copy of the price template (PRT),
and this can be changed as required.
If the user creates a Rental Quote Plan (CQP), the price will be taken from here instead of from the price template (PRT).
More about Rental Quote Plans (CQP ) can be found here: