I have brought a long range science vessel retrofit with one of my other characters. I tried to get the ship with my new character but it requires purchase again? My impression was once you brought a ship it was available to all characters!
Each purchase from the C-Store tells you in the item description as to whether or not the Item is Per Account, or Per Character. In addition, some items are also Rank Related. If an Item is unlocked for an account, it may need Toons to be X Rank to open them to that Toon.