Speaker Invoice Via Audiogon

In case the buyer is expecting something else.

I usually include a screen print of the "For Sale" ad that I used showing the item as "SOLD". Put it in the box when you ship. I keep a copy for my records as well, in a binder.

Yes. You need to accept his offer, (or if it was a Buy It Now). Then add the shipping cost, (even if it is zero). This will close the sale and will send an invoice to the buyer to pay from.