Thorowgood make an extensive range of synthetic saddles to fit just about any shape of horse, e.g. cob, high-withered etc. The lines include the Maxam budget range, priced around �150, and the higher-spec Griffin range, costing between �225 - �275 depending on style. Their website is www.thorowgood.com.
Another range is made by Wintec, prices similar to or slightly higher than Thorowgood's Griffin range.