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 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.

The market for many items here is very thin. In a thin market you have two choices, just wait for the right buyer to come around or reduce prices until sold.

In a very thin market, past sales are less a predictor of what you will currently get than they are in a dense market, IMHO.
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
It seems to have been a buyers market here for some time now. I’ve sold a number of things in past year or so and received a reality check. As with all commerce, something being sold is worth only what another will pay.
I listed preamp for $1300 as it is a B  model. The offer was $500 less than asking price. I am willing to reduce the price if it is a reasonable offer.
 Thanks for all the advice.