Hello!  TLU cels did indeed go on sale (what was it, about a 
year or so ago?), and at that time they sold for around $50-$100 or 
so each.  Then they mysteriously disappeared from the market...
whatever made the available dried up.  Now you can 
find them occasionally on eBay, but they go for a LOT more 
than they did before (I bought one for I believe $50-$60, 
and a sister cel to it sold for $300-$400 on eBay).  You 
will sometimes find Usagi's House (http://www.usagishouse.com/)
auctioning one on eBay, but I don't know of any cel sites 
that currently have cels from that movie for sale.  Good luck 
in your search!

Talia