I'd have to agree with Jennifer.  I love Douga and Genga.  
I usually don't think twice about buying a cel that has a 
matching douga.  But I do think twice if it doesn't have one.
....Unless it's a really special one to me, in which case it doesn't
really matter.

I was buying one of those special ones (w/ out sketch) last year at 
AX and this guy ahead of me in line was like "you're gonna buy that 
without a sketch?"
Me: Yup!  
It was special enough that it didn't really matter.  ^_^

But if I could have my way all of my cels would have their matching 
dougas and gengas!  Bwahahahahaa!

Then there is the "birth certificate" aspect.  By that I mean it is less likely 
for a cel to be a fake if it has a douga/genga.  But of course there are 
exceptions to this.

Ja ne,

Kelly  ^_^