Where you go to actually purchase the unlock (say within your Legacy window) there will be a button to either purchase the Charcter only unlock, Account-wide unlock (usually with CC's) and the option to purchase with Credits (but usually only the Character unlock).
You may be seeing the information in the Cartel window but you have to open your Legacy window (shield symbol on your HUD, can't remember the shortcut key) in order to actually purchase the unlock.
Hope that helps.
I will look in the Legacy window and see if I can find it. I don't remember the hide head slot or anything like that in there, but I will look again just in case I missed it....