Here's a not-so-rhetorical question for you.
Let's say that somebody you've done business with
before really really wants something out of your
personal collection, and you've told him before
that you don't particularly want to sell the item
(let's say it was one from your favorite series 
and of rare secondary character).  Let's say the 
same person turned around a while later and 
offered you a large amount of money which was
1) more than you paid and
2) more than you would've been willing to pay.

It's obvious that this person wants the item more
than you do, but you like it, and don't really
want to sell it.  Nor do you particularly need
the money at this point in time.

Would you consider it selling it?  Does everybody
have a price, or are some things truely not for 
sale?  What would you do in a similar situation?