I have had good experiences, buying and selling on Audiogon.
I'd say it's OK to exchange emails on Audiogon before a formal offer is extended on the site. But I would avoid dealing with a buyer who wants to consummate the sale outside the site. I had one guy who emailed me thru Audiogon, asked me to call him, which I did, and we went back and forth on the phone, came to an agreement on the price (which he said he'd pay in cash), then when he arrived in my driveway said that he rethought his offer and wanted to buy the unit for $600 less than we agreed upon. With no formal offer on Audiogon, there was no "trail". I wouldn't deal with people like that.
I'd say it's OK to exchange emails on Audiogon before a formal offer is extended on the site. But I would avoid dealing with a buyer who wants to consummate the sale outside the site. I had one guy who emailed me thru Audiogon, asked me to call him, which I did, and we went back and forth on the phone, came to an agreement on the price (which he said he'd pay in cash), then when he arrived in my driveway said that he rethought his offer and wanted to buy the unit for $600 less than we agreed upon. With no formal offer on Audiogon, there was no "trail". I wouldn't deal with people like that.