He may be talking about the plastic bases to hold the standees.
I don't think you can just buy base cards, but I know plastic bases are fairly easy to come by.
ooh! Good point! Well, then. The fighter counts from above still hold. There were 5 little plastic bases in Devastation and 2 each(?) in War Remastered and Fate? So there should be missing around 49. But: Add to those another 4 for the bosses in Devastation. So at 53 or so, you should be fine