Tony- I think you captured what my opinion on cel 
signatures exactly.

For the cel owner who gets the cel signed, it 
represents not only an awesome cel being worth 
more to you, but an assload of memories to boot! 
The thrill of meeting the person signing (to be 
sure), but other things as well. When I got my 
Tasuki cel signed I remember LOTS of things and 
treasure them dearly! Everything from the sights 
seen on the bus trip to Animazement, to the 
absolutely wonderful cosplayers walking around. 
It's a once in a lifetime experience that you get 
to look at every time you open your cel book!

However, if you're the one buying the autographed 
cel, there's no memories to take with you. 

That's why it's my personal opinion that only 
cels that you cherish deep in your heart should 
be signed (whether you paid $20 or $2000). It 
will mean FAR more to you than it will to anyone 
else. Getting a signature just so it raises the 
monetary value of the cel is just plain stupid.

~Nabs-chan
(Although, it did kinda worry me that Watase-
sensei took my cel OUT of the bag, signed it, 
then put it back in. I would've preferred her to 
sign the bag than the cel. But what do you 
say? "Hi! Um... don't sign my cel. I don't want 
the ink from your siggie to eat thru my paint."? 
Not matter HOW you put it, it sounds ungrateful 
and rude. ^^;;; )