A large number of the OAV cels that I've seen 
have been resting in private collections, which 
makes me think that I've long since missed the 
opportunity to get any cels from those at a 
reasonable price -- every once and a while, 
though, someone will update with a few cels from 
the OAV's, but not that often.

I haven't really been collecting long enough to 
make a definitive statement about the TV series 
or DASH!, but TV seems to be what's in 
circulation now (I believe the series aired in 
1998 if I'm not mistaken).

I can't remember what the date was on DASH, but 
I'm thinking it was slighly earlier.  I'm not 
sure if the cels from it have just come and gone 
already (which I doubt, since I haven't seen any 
in anyone's collections, and I'd think I'd have 
found at least one looking through half of the 
galleries linked to on the cels ring & on taro), 
or if most of the cels were just never released.

I suppose the shortness of the series lends 
itself to a smaller pool of cels in general, as 
the OAV's are only 6 eps, and TV and DASH! are 
each only 12 eps (as best as I can tell, since 
only 6 eps of TV and 4 of DASH have been subbed - 
if anyone knows of episodes subbed beyond that, 
let me know).

It's about 5:30 am, so I'd better get off to 
work...
Tim