I like your kingdom of men idea.. to save money you could try some historical ranges. I think these berber troops might fit the bill.
http://www.miniaturedesignstudio.co.uk/berber-spearmen-304-c.aspWas thinking of using these myself as an evil human kingdom to go against my Greek themed human forces of good.
Wargames Factory makes some persian soldiers that could fill in back ranks of units pretty nicely. and they have cheap cav as well. They are going supper cheap at the moment. 12 troops for $2.40
http://wargamesfactory.com/webstore/individual-sprues-and-bases/s041-persian-infantryI purchased some and they are'nt half bad. not quite mantic in quality but for 20 cents a piece I can deal.
