We don't mind so much people asking if x is a good price for buying a car. It's just the threads that end up as an advert...[/quote]
You could perhaps check this site
http://audiokarma.org/forums/index.php It's US based but has the same section layout as the Fiat Forum. They've got a seperate section specifically for queries about market value, and for members to post links for third party items (such as Ebay listings) they think could be of general interest. Anyone using it as a free advertising site for their own sales first gets a polite reminder, then a not so polite reminder to use the (paid for) classified section.
As a newbie ti Fiat Forum I was reluctant to ask too many `how much should I pay?' type questions, but having now bought one of the things I'd be more than happy to post a `this is what I bought; this is I paid etc' in the right section.