My philosophy:

Whenever I buy a cel, regardless of price, one of 
the things I ask myself is, "if I ever decide 
that I no longer want this cel, or believe that 
the money I paid for it would mean more to me 
than having the cel, would I be able to sell it 
at my cost?"  If the answer is no, I won't buy 
it, even if it's a dream cel.

I agree with you that nothing is forever, and I 
doubt I'd enjoy my cels as much when I'm 80 as I 
do now.  I'd like to think that if I tire of my 
cels, I'd be able to find homes for them, without 
a great financial loss on my behalf.  And, for 
the same reason that I won't be getting a tattoo, 
I know that I personally will not enjoy a dream 
cel forever.  ^_~

Zenj