Money, it's got to be the least fun thing about 
collecting anything -- well that and all of the 
anal retentive habits you develop so that you can 
take care of them :).
(If I think too deeply about how much I've spent, 
I'd give myself ulcers.) 

Going through my collection though, I don't 
regret a single purchase -- well there's one I'd 
like to get rid of (does anyone want a Riel and 
Hamelin cel? Anyone? No. I thought so), but none 
that I'm torturing myself over. I think 
Moookyblast has the right attitude -- if it can 
still make you smile months after you've paid the 
bill, than you've probably made the right 
decision.