An interesting Dilemma.  My first reaction was to consider the creator of the character naive for wanting to restrict add-ons.

Upon further review, i think it was unfair of the merchant to create and try to sell something. 

I guess it all depends on whether the read-me file that was included with the character explicitely stated that no commercial add-on items could be made.  This could be a misunderstanding as opposed to a case of blatant "just try and stop me".

True, the vendor is not breaking any laws, but it is a matter of honor.  The community is now being punished because of this as the creator of the original character has pulled it from circulation.

Oh, and as far as what ratscloset said concerning copyright, does fan-art or fan-fiction threaten copyright?  I'm not certain that a fan 3D mesh would either, but these laws are always so grey.  I remember a case about someone who was giving away 3D meshes of liquor bottles (can't remmber the brand) and they recieved a cease and desist notice.  Also, many years back (1990's) wasn't there a huge case where paramount was trying to shut down Star Trek fan sites?

All I know for sure about the copyright thing is if I use something in a commercial project that is a fan-mesh that I could be in a lot of trouble.  That's why I really get angry at fan meshes being sold in stores, especially when they do not reference the original source!