Products and services can be flagged as having any of the following:
Variable Upfront Buy Price
Variable Recurring Buy Price
Variable Upfront Sell Price
Variable Recurring Sell Price
This is set on the item record in the price book.
Ranges can be defined for sell prices, allowing users to set a price within this range when quote building.
If you enable these ranges all users will be able to edit the buy and sell prices by default. You can disable this for individual users by checking the respective customisations.
Disable Quotation Service Buy Price
Disable Quotation Service Variable Sell Price
Please note that default sell price values must fall within this range.