Vanity items, unless otherwise noted, are bound to the sub-class the purchase is made for.
If you buy a vanity item for the Agosta, you will have it available for the Trafalgar, Otranto. Vigo, and Athos.
For the Cerberus, you will have the items available for the Orcus, Ceres, Aion, and Feronia.
This is still a very greedy design since you have 5 € (to 3,65 if you go vor the 100€ pack) to have a 500 GP scin for one supclass.
Yes i know there are some for 400 200 and 100, but is color changing realy that cost intesive for your designers?