Audiogon is both an audio market place and a forum. There is no income from the forum. Therefore if folk like you come on to promote your own product, but try to sell it by inserting links in your forum posts, then Audiogon would have no income and the forum would not exist.
You can sign up for the dealer Program or place ads.
It would be good etiquette if you comment about product that you manufacture and sell that you would at least put a dealer disclaimer in your moniker.
I have heard your arm and appreciate the ingenuity that has gone into it.