Hi Danny,
Yes this is possible - but it's a bit of effort. The test price dialog isn't public unfortunately (It seems this was intentional - it wasn't quite refactored enough to be easily used in isolation from the price scheme maintenance form) - fortunately it wasn't
that much work to copy paste and refactor that into a dialog within a plugin.
Attached is a plugin which adds a "test price" button to the ribbon of debtors and inventory maintenance - when pressed the test price dialog shows, and is pre-populated with either the debtor or inventory item - the user must then select either a debtor or inventory item (depending on which form they invoked it from), and select a quantity.
Mike