You have to compare the U- values or the K-values. The lower the number the better it insulates.The Kingspan stuff is very expensive . When you compare like with like the EPS ( expanded polystyrene ) is cheaper than polyurethane. Around 30% cheaper for the same insulation propertys. But you have to compare brand with brand , there is heavy and light material , the latter insulates better and is cheaper. K- values are have to be published on the packet, that is law.