Hard plastic or soft? Standing or moving? Getting hold of just one might be a bit of a challenge, as they come in sets. Italeri are IMHO the best sculpted (and also the most 'expensive' and have saddles etc moulded on; Armies In Plastic are cheaper but not so well sculpted but they are without moulded on saddles etc so might be better for you; Airfix are between the two and are 'bare backed'; Britains are also, mostly, nicely done but have a support under their bellies...
I could let you have the odd Airfix, Britain or AIP if that is all you need?