When I was writing Dead Gods I had these little packs from Warhammer Underworlds in mind, since they're fairly inexpensive (buy one and have a complete Warcult).
Skaeth's Wild Hunt could be a good one for The Pale Druids. Knight, Musician, Beast, Runner, Bowmaster.
Another good source are Frostgrave, Perry miniatures, Wargames Atlantic or Mantic. By far cheaper than Games Workshop (but I agree, their Underworlds and Warcry minis are wonderful), and ideal for kitbashing, like this guy.