I've heard of recasters making resin versions of GW stuff- if you ask around on the Specialist Arms forum you may find something. Other than that, the only plastic Warmaster troops I know of are from the Battle of Five Armies boxed game (which was Warmaster- maybe Warmaster v1.5). BoFA had some nice models, but unfortunately I don't think it was ever advertised- I only found it on the GW site by accident one day, and it was canned soon after. You can find the models through trades and on eBay, but (on eBay at least) they can be very expensive.