Well, it happened to me before, but my story is
somewhat different than yours.

The seller told me someone has else made a higher 
offer for the item that I wanted, and told me to
counter-offer it.  I said forget about it, I'm not
going to counter-offer it.  Then days after, he
told me the item is available again, and asked me
whether to buy it again at the price that we
settled before.  Then I suspected that he lied 
before by telling me someone has made a higher 
offer, but the fact probably is no one has made 
him any offer, he lied to make me think someone
else was bidding against me.  After that, I don't
bother to return his emails, he is greedy, and he 
deserves what he has done.  

Depending on how much you like the cel, if you
really like it, go ahead to make a counter-offer.
But for me, I will just forget about it.  Move on
and hunt for better cels at better prices.