Autozone sells a Metric O-ring assortment made by Dorman for less than $8.
Dorman 172 piece O-ring Value Pack #799-450
In it are 24 of the 6mmUDx10mmODx2mmW O-rings that you need for the bottom of the Oil Filter Stem: enough for 12 Oil Filter Changes as you need 2 O-rings each time you change it.
The 10mmIDx17mmODx2.5mm in the kit fits the bottom of the Filter Bolt; you get 24 of those in the kit.
The 14mmIDx19mmODx2.5mmW appears to fit the large upper O-ring (if you have the Filter Bolt that takes 2 O-rings) but I have not actually tried that yet.
You get a total of 172 O-rings in various sizes.
84 300D, 82 Volvo 244Gl Diesel