Audio valuations


Is anyone else interested in determining a fair value for used high end equipment? I understand we all try to sell and buy our equipment at the best price, but where to start? I recently listed
a item for sale and set a price that I thought was competitive based on very limited past sale information. I did receive an offer that was $500 less than asking price. Was I too high or was the offer too low. It would be helpful if we could see what others sold their equipment for and the condition of the equipment. I want to sell my equipment, but I don't want to give it away.
Any thoughts on this matter?
elf1
I do that daily and as a result of such endeavors, I'm not offended, frustrated or worried about low offers. All I do is agree or disagree. 
If you reveal component you want to sell, I'll throw few cents...
I guess I should have been clearer with my question. I am looking to sell a tube preamp that can be considered vintage. Needless to say it is difficult to find many of these AR SP6 preamps for sale. If Audiogon, US audio mart, ebay, etc. would provide the actual sale price would be helpful. I understand that vintage equipment to a collector could sell for a different price than someone who wants to use the equipment. I am sure all members would appreciate what other items sell for. 
To answer Yogiboy, I have the preamp listed on US Audio.

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There are not many sales but I would guess that should sell for 1200 - 1500

Audiogon has much more traffic and items sell faster than other sites IME