Book values are still important but they are valuable for online trading on message boards, blogs, etc. In recent years, there have been a host of hobby message boards pop up (some with 25,000+ members) where trading is very popular. Yes....trading is back...thanks to message boards, blogs, etc. One website in particular
http://www.thebenchtrading.com/ has over 7,800 members and focuses just on trading. Some message boards (like the Bench) have advanced "Trade Manager" features to help collectors track the status of trades, etc. That being said....on these message boards....Beckett pricing is the standard.