How to buy used key fobs - SPA/CMA key fob and config guide

[nugget]

Couple updates:
1. I tried programming one of my wife's S60 key in my S90, and it stopped working on the S60. Later when I programmed it in the S60, it showed key already exists, and I had to remove all keys to reprogram it.
Same key for two vehicles doesn't work (not surprising lol)
2. My S90 didn't originally come with a care key, and '214 Restricted Key Function' says 01 Without restricted key. Despite that, programming a care key from eBay auto attached it to a profile that was restricted. Likely because my car didn't originally come with a care key, there was no setting for the speed limit either. It's a 2018 S90 and was likely one of the first SPA models, so acts differently

[bretalanwest]

For anyone that might be interested in having a backup for the fob, I was able to get keys cut at my local Ace Hardware. I called ahead to confirm after going to one location and being turned away. They were reluctant but ended up doing them for free after I mentioned that we called ahead. I bought a 10-pack on Ali Express. It took about 10 mins to cut because the metal is so denser than your typical house key. Locksmith quoted me 50$ and another quoted me 150$. A 10-pack of blanks costs 11$. If anyone needs/wants a key blank, DM me. I will hold on to them for a week or two and then recycle.

[ChainedAlice]

Can you program a normal key to be a Care Key?

[bretalanwest]

Can you program a normal key to be a Care Key?

Having just gone through the steps - I did not see any options.