What would you do?

Put the evidence together and present it to whoever is in charge of the auction site. Let them determine if it's an issue or not.

does anyone really ever buy anything at auction?

in my 15 years on Audiogon and hundreds of transactions I've never participated in or even paid attention to an auction. it's all just 'for sale' stuff......so there is no relevancy to these comments.

nothing here to see, move along

I'm still waiting to read about whom you think the culprit is?
It could be worded as to imply this might be happening.
Too bad you had such a bad experience in audio, most out there are honest, but one does need to be careful more fraud than ever going on.

Audiogon does auctions where audio manufacturers sell equipment? I didn't know that. I thought it was all person to person/ used stuff here..

So to be clear I'm not talking about auctions on this website. This is on another auction site that is, uhm, pretty well known. And the products in question I guess you would call 'audio accessories' although they do make speakers.

Post twice that will help?