I have the o-rings. I don't know if I have a complete set, or how many make a complete set. (Some are used in pairs.) I don't know the specs for any of them. And while I can (and have) measured them myself, some are difficult to differentiate between metric and american specs. Which ones are the harder BN90? For me it's difficult to tell... the squeeze test is not useful as they get smaller or larger.
I recently replaced all the o-rings from the regulator to the bottle, and all is fine. I question whether I installed the (nominally) wrong size o-rings in the wrong places, particularly in critical areas like the regulator. For instance, the smallest o-ring in the reg appears to be a softer 005BN70, but the next larger one on the same stem appears to be metric 1.5mm x 7mm in 90 hardness.
There are two tiny o-rings (the same size) in the kit, but I am not convinced they are the same hardness.
It's not about spending money, it's about acquiring knowledge.