I usually avoid make offer type deals unless 
there is something I really want.  Thus, not all 
that many cel purchases recently for me due to 
the insane amount of people wanting offers on 
their stuff.
And the phantom buyer thing - argh.  There was a 
cel I really wanted but was too late to get that 
sold for $170.  When the person who got it put it 
up for offers, I offered $400 (thought it was a 
good markup for them).  They said that in the 
past they had gotten an offer of $700 for it.  I 
didn't reply, but thought they were stupid then 
not to have taken that money and run.  They then 
tried putting the cel on ebay trying to see what 
they could get, ended up not selling as minimum 
reserve not met and end bid was lower than my 
offer.