. most studio's will release photo's of an up coming anime's release.
. usually, the Manga is the selling origin for the funds for the anime
and as such -- they are not releasing anything new! Therefore, it
would possibly be best to grab and scan the Manga before the CELs
are even drawn!
.. the only other place I can think of would be to have a friend who
works at the studio where the Anime is being produced and get a
bad cell drawing that was not destroyed when tossed out!