Activators seem to sell very well, as do the deluxes, Voyager Starscream also seems to be very thin on shelves as well.
I think the "movie" named figures are selling better due to their exposure in the movie, thats the only reason I can think of as to why there are more Prowl than Bumblebee figures on shelves.
Lockdown does seem to be the shelf warmer of the moment, not really a surprise since he is only in a couple of episodes in the first 2 seasons total.
Looking For: Wreckers Saga TPB Collection (with Requiem)