I love backgrounds too. I got one on the way, 
that is VERY close to my new Nuriko cel. It was 
easy because no detail, just a blank yellow with 
a touch of blue background was in the screencap 
and artbook, but, the one I got was all the 
yellow color-close to it though, but it should 
make it look more prettier:)

Still need to watch my FY tape today and check 
what the background for my other Kouji cel looks 
like. Would be a sweet thing to find one:)