Wow, that's amazing. There are some fun legacy unlocks that you can buy with creds but your legacy leve.
Save up for 41 stat color crystals off the gtn. Hawkeyes and eviscerating and indestructible crystals are good for leveling. Some of the newer ones are fairly cheap. Just limit the search to level 11 or you'll get all the level 50 only crystals.
Once you get a crystal you can unlock it in your collections and give it to all your toons and their companions.