Well, there is a some difference between Gundam 
Wing and Escaflowne cels in terms of quantity 
available.

Althrough GW is 52 episode series, people think 
there are lots of cels for 52 episode series, 
however if you watch the entire 52 episodes, I 
have done so 3 times, you will notice, the 5 main 
characters or even the Gundams don't show up 
much, compare to shows like Tenchi Muyo, since 
there are so many characters in Gundam Wing, and 
so many battle scenes with Mech, when you compare 
it to DBZ, it make GW seen like a 3 episode OVA, 
we all know the price for good quality DBZ cels.

Even if you compare to 26 episode like 
Escaflowne, I can guarantee, there are far less 
Heero cels than cels of Van, or less Duo cels
than cels of Allen, even for 26 episodes, Van 
show up far more than Heero did in 56 Episodes of 
GW

There is virtually no Gundam Wing cels in any of 
the dealers site right now, and even on ebay, 
there is no where near as much as a while ago.