I've only a blue belt, so I shouldn't be able to own any elf-coloured items.

However, I was able to place an buy order on an Right Leg Elf Motion Trail, and later transfer it to my inventory and activate it. I'm not sure if it will actually show up in-game, as I haven't played with it yet, but as far as I know I should not even be able to have it in my inventory.

/Edit: Does show up in game. I have a working right leg elf motion trail.