No, they do turn up eventually. Can't remember how to get them, but it can be done. I believe I found the Mario & Yoshi one during the Brinstar Escape sequence of Adventure mode, and I think Samus Unmasked rolled out of the Lottery, but I'm not entirely sure. AR is probably your best bet.
10000 posts at last! w00t! Okay, I'm off into a quiet retirement. Don't bother me.