Greetings,

Ah, Rayearth.  Haven't seen much of it myself 
though I do collect some of the series.  The 
area you're heading into is late into the 
series, probably talking about the Chizeta twin 
princesses, Tatra and Tarta.  Since you mentioned long wavy hair, 
I'll assume you're talking about the elder 
sister Tatra.

The girls are, again, from the latter part of 
Rayearth, and although they aren't exactly evil 
bad guys, they are in an antagonistic position 
as they are trying to claim Cephiro (the land of 
the Magic Knights and general do-goodery of the 
show) as their own in order to bring their small 
country more land.

A pan cel with Tatra holding a black ball, 
though?  Yep, I've seen a few cels from that 
sequences here and there.  Here's a link to one such gallery that has it on 
display.

I've also seen it on sale before, though I'm 
afraid I couldn't tell you where.  On the dealer 
page on which I found it, the pan cel was going 
for about $180, give or take a few dollars.  In 
general, decent Tarta/Tatra cels go for $50-
$100, while really nice, popular shots usually 
lie in the $150 range.

Hope that helps,
Pitten