My last set of Busa pistons cost £57,just check the ring gap to make sure they are in spec,have t paid more than £70 for a set of Busas,my bike gets used regularly and has done for the last 3 years,the set that are in my bike have been in for the last 2.5 years and have been running 10/11 psi most of the time with a high of 18psi ,they are very cost effective.Rebore and pistons came to £200.