Is there a list of Companion Customizations and the vendors that sell them anywhere?
Taris, Belsavis, Ilum Base (this one currently has nothing on it however)
Ilum orbital station and Faction Fleet (these require you to have an authenticator)
Not really a list but most of the items have the vendor locations in the comments. http://www.torhead.com/items/name/customization
Originally Posted by Zotan
The VIP lounge also sells some. Not sure if they're unique though.