Bat Wings
 

Pretty sure these reagents aren't supposed to be sold, at least not in classic. Anyone able to find or remember when exactly they were added in?

I remember them being available since at least early Kunark, which is when I started pursuing other tradeskills. There are references to unlimited batwings being on vendors in EC, Freeport and a couple of other places on Alla's from May of 2001 (earliest I could find). There are no references to bat wings in any patch notes (I used Alla's archive) up to July 2001, which was as far as I looked.

It's possible they were added post classic, but I can't find any evidence for that. Maybe someone else will remember more clearly.

I also remember having to collect these as drops (like with bonechips), and they were definitely not vendor-sold for quite some time.

Early Kunark is earlier than I would have guessed, but maybe I just didn't notice that they had become available this way.

What continent? According to what I've been reading, they were not available on Odus when they were available on Antonica (in relatively few places).

This would have been Antonica and Faydwer mostly. But again, I probably just didn't notice that they had become available this way.

Well, I need to reiterate that I really don't remember for sure one way or the other. They were there in early 2001 for sure; beyond that I don't know.