I know exactly what you guys mean. ^__^;;  I've 
got such a horrible memory!  I tried keeping a 
file of people who'd contacted me about cels, but 
nowadays that I can only get online/check e-mail 
via public computers, it's really hard to keep 
those kind of records.
I know of one specific cel in my gallery that I 
got a question about, approximately a year ago, 
from somebody I didn't know, and I can no longer 
remember the person..  I later had somebody else 
ask me about the cel.  In the end, I just decided 
that I won't sell the cel. 
From that time onward, I've only ever given dibs 
to people that I know fairly well, and figure I 
can remember. ^-^;;  It creates some unfortunate 
difficulties, but I'd rather be upfront about it 
rather than make a promise my shabby memory 
cannot uphold.

~Mala