What keeps making me nervous is that I'll put a 
cel in my cart, continue shopping, and then go 
back to find my cart empty.  ^^;  I guess the
cart times out after a certain period.

I got that "please note that this item is not
in your cart" message, too, and just clicked
"buy this item" a second time.  I -think- I got
the cel I wanted (I wasn't stopping to read
all the fine print ;), the one of Kozue and Miki
together from their duel in the Akio saga.