I am no MVP but let me try. A simple solution is to copy the list of numbers
in the price list to another place (may be another sheet) and set a
conditional format in the first cell of your price list in which it applies a
format (color) if the cell value is not equal to first cell in the copy. When
you set this condition do remember to press F4 a few times so that there are
no $ signs in the cell reference (of the first cell in the copy). After this,
click on the paint format button on the toolbar and select remaining cells in
the price list.
Initially nothing will be visible but when you change a number in the price
list, it will get colored.
Whenever you wish to reset the changes (e.g., every morning) you can copy
the price list numbers and paste them over the copy you made earlier. It is
preferable to use Paste Special > Values while pasting.
If you like, you can record a macro and name it Reset for doing this, and
assign a keyboard shortcut or a custom button to it. This will make the task
cleaner.