[Vicious Love]

Agreed, PvK. The hunter spider is a mainstay unit(Or the higher-end variant of the spider rider mainstay unit, at any rate). Without hunter spiders or spider knights/riders, a Machakan army is simply incomplete, and spider troops are the backbone of any Machakan raiding party.
Gryphon Riders, on the other hand, are a more specialized kind of unit. They fill a very specific niche which some nations(Particularly ones without air magic, blood magic, or flyers of their own) can benefit tremendously from(Bringing down a VQ without flyers is always tricky, for instance).
If they're overpriced, it's because they're exotic indy troops, meant to be used under specific strategic conditions or supplement existing armies, not national troops, which are supposed to be able to win wars on their own.

Update: Point in case - The Last thing anyone expects Atlantis to do is start striking at undefended enemy hinterlands with Water-9 blessed flying shock troops. Caelum might benefit a bit less from indy flyers, but that's why they're indies.

[ June 14, 2004, 21:13: Message edited by: Vicious Love ]