I had one dealer sell me an item that had been 
listed on his sale page.  After I submitted 
payment and he received it, then s/he discovered 
that s/he had previously sold the cel but had 
forgotten to take it down off his sale page.

Another admitted that s/he simply could not find 
the cel any more and was unsure whether it had 
been sold or was simply lost somewhere.  (This 
happened before I submitted payment, however.)

While I was disappointed both times, I did not 
take offense either time.  The first dealer 
subsequently offered me a very good deal on an 
even better cel that s/he had not yet put on on 
her/his sale page.  

While I'm not condoning sloppiness on the part of 
dealers, I'm also recognizing that there aren't 
many people who sell enough cels to make a full-
time living off it, so we're dealing with people 
who are running this kind of business in time and 
energy stolen from their day jobs.  Kusu happens, 
all the time, in such circumstances.

So I'd be forgiving, but firm about what you 
want.  If you don't want the other cels, ask for 
the one you want and a partial refund.  And part 
on as good terms as you can: as one of the other 
replies said, that darn cel might just turn up 
next week behind the bureau.