It comes in handy to keep track of your cels when 
you're faced with a big purchase, like a 
downpayment on a house or a custom guitar. :) 
It's funny, today my boyfriend pointed out that 
if I sold all my cels at the price I bought them, 
I could easily lay down a house downpayment. I'm 
not getting a house just yet, but it's nice to 
know.
   I remember how much I paid for most of my 
cels, but I have 100+ and it's nice to have them 
catalogued with exact prices, dealers, and dates. 
When I sell them, I like to know if I have a 
repeat buyer. Also, when I'm buying 10 cels from 
different dealers at once, I like seeing on one 
page which cels I've paid for and which I still 
owe. Digging through emails doesn't always work 
for me.
   again, I follow the anal approach, and I'm 
shocked that so many others do the same. I'm not 
saying that you should do this, especially since 
your way works for you. I'm just rambling. ^_~

/mina