Don't know if such a suggestion was posted already, but here is my opinion.
In every mmorpg on the market when the game have a store , you can buy 100000000 mounts of the same kind just in different colors. The game has a recolor system and you can buy multiple colors. Why not give the players control over the colors of the mount? And you can sell all the other things extra like the saddles , mount tattoos and so on. That would be the perfect way to do it.
The other alternativ way would be , that your system knows when you have a "base mout" lets say the grey base wolf. If you buy a other colored wolf (only recolor not with extra tatoo , other saddles etc.) you will own a discount. Let's say normally a mount cost 1500 crowns, with the discount its only 900, cause its a simple recolor. That would also solve the complaints that mounts are to expensive.