Oops - no more advertising of gigs? No more advertising of "I've got a new CD for sale"? I don't think so.

I don't see a problem with putting a notice up that you're selling an instrument. I wouldn't like to see anyone advertise enough to look like a dealer and I wouldn't want to see dealers use Mudcat as nothing but a place to put up ads, but a one-off ad would NOT be a problem for me.