Well, I realized that my Undead Army pack from Mantic does not, in fact, have Skeletons, but rather Revenants, which are apparently Mantic's version of Grave Guards. Since I cannot run an army with 10 ghouls and 20 Grave Guard (as fun as that would be), I am going to use the Revenants as 'counts as' Skeletons. Whatever. Now, when I get some of the soon to be released Mantic Zombies, I have my big block of Grave Guards ready to roll. When I say 'some' Zombies, I of course, mean lots. Not only are they a cheap core choice, but you apparently need spares to use for summoning.
This is why I avoid horde armies. What's the WFB equivalent of Space Marines again?