Nice grab! I've seen that cel on YJ a few times.  
I got mine the first time around and then this 
one shows up.  I almost went for it so that 
nobody else could have a similar cel but I 
figured I'd share.  Mine is A7 with a layer on 
top numbered B30.  It's hard to tell from that 
auction what the bottom layer is but you're right 
that it is very close.  You can tell by my cel 
that it's further forward in the sequence than 
yours since you can see more of the Mecha and you 
actually get some flame on the side too.  That 
one is my second favorite only to this one: 
http://fullrage.rubberslug.com/gallery/inv_info.as
p?ItemID=45482  That one is definitely the only 
one you'll ever see since it's an A1 END cel.  
Only one cel in the sequence.  I was surprised 
that I didn't have to fight for it on YJ.  I'd 
love to see your collection if you ever get it 
online.

oh.. as for the background, it's not a 
screencap.  I actually downloaded that image from 
a background that was for sale on YJ and had it 
printed out at kinko's.  The quality isn't very 
good because I had to blow it up to fit the cel 
and then I blew it up more on a color copier.  I 
can send you the file but you'll have to do the 
busy work.  Send me a note using the feedback 
option of my gallery.

shanks