There is a Blue Book on slots that was published about 10 years ago.
Unfortunately, a price guide that is 10 years old can have some very unrealistic prices.
For example, a Caille Roulette is listed at $30,000 and the last two that have sold at auction have brought over $200,000.
If you want to find the Blue Book, just do a search for Mead Blue Book Slot on Google and I am sure you will find a place where you can buy it.
There is also an online price guide available (which I put out). That has information about what prices machines have actually sold for and it is not based on someone's opinion on what a machine is worth. Instead it is based on facts. In many cases it includes the photo of the actual machine.
Go to
www.AntiqueSlotMachinePriceGuide.com to check it out.
Due to the effort involved to develop it and keep it up to date, I am not offering it for free. It is made available by subscription, 14 day and 12 month subscriptions are available.
Dave