I try to keep my collections in order and in the past just used a spreadsheet to record purchase date, cost, etc, but found a great alternative I wanted to share. There is an open source project that combines the spreadsheet interface with a database backend, called grist (GetGrist.com). You can store all your data, add pictures, python code (to pull current prices), and many other things, all for free. The creators hope as your data grows, you will move into a paid tier but since its open source, you can download it and run it locally. (I am just a user, nothing to do with the software) I have been using this for 1-2 years and really love it. I keep my book, cologne, tool, and watch collection in it. Cloud accessible from anywhere (but no app yet). Let me know if this was helpful.