is there a stereo blue book for value of old gear

i want to sell some stuff and need to know its value so i am robbed..
any help would be appreciated
I believe it's called the Orion Audio Blue Book. Most Hi End audio shops should have a copy. You could probably buy one from a technical book shop or go to
Orion Blue Book issued each year. Used versions sometimes available here.
You can also subscribe to the Audiogon blue book. Not affiliated with Audiogon..... totally ignorant.... not responsible when it doesn't work, etc......
It really doesn't reflect true market values. It's primarily a tool for dealers.
Although I have not seen one in recent years, I always found Orion to under value equipment. My suspicion was that it's real purpose was to justify dealer's low ball quotes for trade ins.
What kind of old gear? Transistor receivers from the '70's & '80's won't be worth much, other than a few classic models. Same for most turntables [Duals's & Garrad's]. With speakers, many of the woofers used a foam surround that decomposes to dust over the years.

If you want to tell us what you are planning on selling, we might be able to tell you if you got a "winner" or an eBay special.

The Orion Bluebook & Agon's own Bluebook are more of an approximation than a hard and fast firm price.
its just some linn gear(pre and power tek and basically the cables and arcam cdp blah blah blah...i know its of no huge value but i just need to get the most i can out of it.
Is your old gear fairly common? You could search current and closed auctions on eBay. They usually show everything at least 30 days back, sometimes more.

Search similar gear as well; for example "Kenwood Tuner" or "Marantz Receiver". You will get an idea of value, even if not your specific model.