So on my main collection (55 Topps for those of you living in a cave) - I have developed the following spreadsheet application.
This has evolved over 10+ years into what you see below.
The program allows intercahngeable value databases (currently using 2012 SMR) and populates a NRMT value automgically. This is a very handy reference when I am ebaying and need to know, at a glance, what current valuations are for a given card.
Having accquired a card I can use drop down box to enter grade which then auotpopultes a value based on that grade.
The really useful info is automatically calculated on the "Summary" page.
Never shown this to anyone - but since you asked here it is :