Cels from the series don't seem to be very 
common, from what I can tell.  (I've been 
looking, too, since I really want cels of 
Bantarou, Tsutsumi, and Koinosuke. ^-^;;)  Most 
of the time, when you can find them, they aren't 
too expensive, but nice cels of Jiyu/Jubei 
herself tend to go for $75-150.
It was a short series (I can't remember, right 
now, but I think 13 episodes,) so it's natural 
that the cels would be in short supply.  It also 
didn't get nearly as much popularity as it 
deserved (it's so silly!)