Wow, thanks guys. Lots of info and lots to choose from.
Thanks @punkrabbitt for sharing your crows. I'm going to use them initially till I can find ... or make one of my own.
I want a really big crow, think Eagle size, hence why I was looking at a Warmaster stuff. I think Blood Crows should be huge compared to other birds.
I had a play around with them yesterday, and they are fast. I sent the crow off on 1 flank, and my 2 Warhounds on the other to hunt down the enemy Wizards. As the Wizards tried to back away from the Warhounds, the Blood Crow held one up long enough for the Warhounds to reach ... and eat him.
2 turns of the Wizard not casting spells, a dead Blood Crow, (no cost) a dead Warhound, (20g) and a Dead Wizard.
Job Done.