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.
Speaker Invoice Via Audiogon
I just sold a pair of speakers utilizing Audiogon. My buyer wants me to generate an invoice via Audiogon. I am only familiar with creating an invoice via paypal. Is it possible to generate an invoice via Audiogon?