OYM is very very very rare from what I can tell.  
Someone on the #anime-cel had said they saw one 
cel in a gallery in japan, and it's said that for 
a while Mandarake had one up in their store for 
$10,000 (supposedly a "perfect" shot of the two 
guys, the angel, in the red car).  If anyone has 
seen OYM cel's for sale, PLEASE tell me! ^^;

---Fireye