Go to my group
AG eye spy with my little eye... https://www.facebook.com/groups/189850087831131/for identification help or you can do your own research... your best links to help aid in that are the
American Girl Wikia http://americangirl.wikia.com/wiki/American_Girl_Wiki
Or good old fashioned Ebay www.ebay.com
What is the value? Value is a personal decision... and for collectors items there may not be a market for it at the moment or the market itself could be in a slump..
Best bet is to look under Ebay Sold auctions and decrease a little under their value and move the sliding scale based on condition and availability.. etc.
I usually round the first 5...