If you had a few hundred dollars each month to put towards stock pilling parts for the long term up keep of your W123's what would you get?

The reason I ask is because I just put in an offer on my 4th - 1983 240D. Obviously I am addicted to these cars and want to have them around me and my kids, hopefully, for MANY years to come. It always makes me sad when I'm looking for parts and get told they aren't available anymore. So the last few months I've been buying random parts that I think I may need in the future.

Do you all have any suggestions on what parts to get now that may not be available for much longer? I recently found out that I may have gotten one of the last headliners and cloth piping that runs along the interior B-pillar. I broke an oil cooler trying to get the oil lines off and found out those aren't available new any longer. Was told I got one of the last rear door checks around. Etc, etc.

Any suggestions would be appreciated! I'm addicted..........