How to know the value of a piano (in mint condition)

[ed miller]

I understand that there is much more to appraising pianos than just knowing 
a single listed value, but I can't find a comprehensive guide to "list 
prices".

The only book I know of is the The Piano Book by Larry Fine. I have not 
found it too useful because so often a particular piano or model piano I am 
looking for is not listed.

Also the Piano Book doesn't factor date of manufacture into the listed 
value, all the pianos are listed according to model. I don't understand 
this.....Wouldn't a piano of the same model, but manufactured 30 years 
earlier be worth a different amount (whether it be more or less)?

Can anyone help me understand this, and suggest some other resources to help 
me appraise pianos?

Thanks, Ed