Does "book value" matter?

I've bought a bunch of unopened retail packs and boxes in the past few weeks.  There were those three "nostalgia" boxes -- 2008 Goudey and the 2008 and 2013 Allen & Ginter -- that I blew through last weekend.  Then, during the week, my wife and I were at Target and she encouraged me to buy a bunch of things to open (so she could watch her various "reality" shows that she likes and I can't stand, like Survivor and The Bachelor).  Finally, I bought a few boxes from DA Card World on their "daily deals" page.

So, the cards and the inserts have piled up.  I'm talking about a mishmash of stuff too -- everything from this nice 2012 Topps Chrome Orange Refractor (which was on the front of one of those Fairfield repacks that includes an unopened 2012 Topps pack):

and two of these Nolan Ryan 2012 Topps Cut Above inserts:

to these two inserts from the 2008 Topps Heritage set -- a Chipper Jones refractor numbered to 559 and a Clubhouse Collection jersey relic for Ryan Zimmerman:

So, my question to everyone is this: should book value really matter to me with these items?  I mean, I know enough to store these at least in penny sleeves and a toploader.  But, how much do you look at either the Beckett value or the eBay auctions for cards when you are considering trading them to others?  

Or, is book value really just something that is a rough estimate to determine whether you keep or sell a card? Is it something else?

I don't want to fall into the 1980s-spiral of "I can't get rid of this card for that because Beckett/SCD/Baseball Cards Magazine/Zoltar the Magnificent says it's worth $8 and I'm only getting $3 of 'value' back!"  At the same time, I also don't want to feel like either I'm taking advantage of someone or vice versa in a trade.  

What do you guys think?