I would love to see some pictures of the Corgi paratrooper. Where did you get it? Are there still many around? Do you keep the original storage case?
Back to the original question, I used to keep some spares, but I realized it's useless. Some of them never wear, some of them are "restaurable" -paint, weld, etc-, and some of them, the wear parts like points, pads etc, are and probably be available.
It's pointless to spend money and space in storing parts. You will never need all of them; it is easier to save the money and, when you need any part, offer double that the market price in that moment. You will get anything you need and still save money. Most of the "free to a good home" parts are parts that people bought in the past "just in case" and found out that if they didn't need them after 10 years, they will probably never need them.