36 years of IT experience has taught me that the key is getting good data. You can write programs all different ways but without the data you’re stuck. I think that’s the case here.
A relational database with inventory from all manufacturers over the years would be key for what we want. Then a webpage(s) that everyone to use it would suffice.
People could then create their own roster by entering in the item number, then the page would populate all other data. You save your data to your own instance. Allow people to download their data for backup.
I looked at the Trainz Community and that is what they have. Plus you can buy and sell amongst others. Trainz charges 8% per transaction. Better than Ebay but not as good as here. 😄