A friend was looking for mannequins recently, for a new museum visitor attraction, and he found the best price on the island for new ones was a shop suppliers ( suppliers of shop fittings ) in Belfast. I can find out their name and p.m. you if you want. Think he said they were about £80 each. There are a handful of shop fittings suppliers around the country - if you ask them, they may have some secondhand ones cheap or even free, as they sometimes refurbish shops around the country / replace their old mannequins.