Reply #7: For newer bikes,

[mahatmakanejeeves]

I use the "N.A.D.A. Motorcycle/Snowmobile/ATV/Personal Watercraft Appraisal Guide." Banks are likely to have it, and some big libraries will have it too. It's issued three times per year by the National Automotible Dealers Association.

http://www.nadaguides.com

To no surprise, it doesn't go back as far as 1966. What the item sells for on eBay is probably the best guide there is. There's a magazine for old bikes, Walneck's Classic Cycle Trader. It should be on the magazine rack of all those big chain bookstores.

Last but not least, Hemmings Motor News has bike ads, does it not? It too is at all the big bookstores.