If you're already using an app or even a spreadsheet to track your collection, some collection organizing apps do let you import/export data. Check with the app to see what types of file formats are supported. For instance, if you're importing a spreadsheet, it may need to be in CSV format first.
Most apps that allow you to back up files do offer a spreadsheet option. However, before you add many items, check to see whether the file can be used elsewhere or just for the that particular app.
If you've just expanded your collection using these Amazon shopping hacks, you may not look forward to adding everything in. If you want to add a large number of items to an app at once, quickly entering data into a spreadsheet with the appropriate column names (names should match the fields in the app) and importing it may be faster.