Genuine Lotus discs are £100 each , EBC on ebay are about £130 a pair. Make sure he gets S1 as S2 are different. Correct size is 282.5mmdiam and 26mm thick, service limit is 24.9mm.
I'm just about to change all 4 on SWBO'S S1. Car has covered 40k without any issue of warping, how's he done that? check wheel bearings and balljoints as these could have play inducing wobble under braking.
Phil S7SVN