I grew up a comic book collector too, and bagged 
and boarded my rarer stock.

I bagged and boarded a few cels, too.  The paint 
does stick to the acid free boards.  So these 
days I tape on the backing board to the back of 
the bagged cel, keeps it nice and sturdy.  I use 
Life Magazine Size bags and boards.  They  work 
great, even backgrounded cels and oversized pan 
cels fit.  

I store them in the portfolio cel book, but they 
tend to get very heavy, they can also be stored 
vertically in a box or hung up on the wall, 
whatever you like :)