I'm going to keep this thread updated with various deals on Quake 3 I come across. Let me know if you see any others.
Aww, missed it! Well, I already have it on Steam, so there's not much of a reason for me to get it on gog other to support DRM-free platforms and I think I'd rather donate to OpenArena because Id Software isn't Id Software anymore...
Will update this thread again when I find another deal.
Updated with Humble Bundle Black Friday deal
Updated with Steam's deal.