What I do is keep a list of people that have said 
they are interested in my cels, along with a 
notation of exactly which cels they wanted. The 
list is kept in the order that they contacted me. 

If I decide to sell the cels in question, I go 
down the list and contact the people one at a 
time, giving them a set price and X number of days 
to reply if they accept. I make it clear that if 
they don't reply within the time limit, it will be 
offered to the next person on the list. 

If I don't have anyone on my list for a particular 
cel, or all the listed people fail to reply ithin 
the time frame, I offer the cels for sale 
publically.

I take the system very seriously, as people who 
have bought from me in the past can attest. 
Sometimes I've contacted people more than two 
years after they indicated interest -- long after 
they assumed I'd forgotten about them! I try very 
hard to be fair. 

Selling to folks with the most money isn't the 
point. The only time I have ever done that was 
when I was trying to raise money for the Allen OP 
-- and in that istance, only cels that did not 
already have dibs on them were sold to the highest 
offer. Cels with dibs were sold in the same manner 
as always -- I gave the person on my list a set 
price and a time frame. In many instances I was 
offered more money by other people for those cels, 
but my conscience requires me to keep my word. 
Sometimes I wish it didn't, maybe then I'd be 
rich! ^_^

My god this is a long message. This is what 
happens when I go away for a week -- I come back 
feeling chatty. ^_^