On the plastic front, there are only two sets: Persian Infantry and Persian Cavalry from Wargames Factory. I have no idea how easy they are to obtain, but in any case they are rather limited in poses.

On the metal front, there is also a range from Wargames Foundry. Do not expect them to be any cheaper than Warlord.

https://www.wargamesfoundry.com/coll...ns-older-range