When using the NGC or PCGS market values I tend to subtract around 20-30% from them, especially if yours are not graded and slabbed by them.
Also look at NumisMedia FMV @
http://www.coinprices.org/ I find their site to be fairly accurate on the classic coins. Pricing can be tough as almost any book will be out of date as to current price by the time it's published and hits the store. Online sold pricing is really the best example, but can still be problematic if you are pricing coins that are not generic and almost exactly the same as yours. So also take the online prices with a grain of salt knowing that fact.
"Buy the Book Before You Buy the Coin" - Aaron R. Feldman - "And read it" - Me 2013!
ANA Life Member #3288 in good standing since 1981, ANS, Early American Coppers Member (EAC), Colonial Coin Collectors Club member (C4), Conder Token Collector Club member (CTCC), Civil War Token Society (CWTS) member, Liberty Seated Collectors Club (LSCC) & Numismatic Bibliomania Society member (NBS), USMex, Member in good standing, 2¢ variety collector.
See my want page:
http://goccf.com/t/140440