Get yourself a copy of Vintage Guitar Magazine. It contains a small price guid that extends monthly. However the goodies or in the hundreds of ads from dealers all around the world. Most of these ads are itemized by type, brand and age of the instrument or amp. Flip through the ads and search for the model guitar or amp you need info on. This is sometimes a better way to find prices because you can find out the current retail market values. Keep in mind that wholesale prices are usualy 2/3 or 1/2 the retail price and a "vintage" guitar or amp is only worth what someone is willing to pay for it. What guitar/amp do you have a question about. Some users here can give you pretty close estimates.