When I replaced mine it was the same price to buy from a Lotus specialist, my usual bearing supplier didn't list them for some reason.
If you want to try your local suppliers the original fitment was supposedly from the Ford Cortina, (UK) although I don't know which model - I think it was the Mk2 but not sure.
RHP 6/W1-5057 ID 38.1mm, OD 68.6mm, 15.6mm thick. Rounded bearing surface to go on the "fingers" of the cover plate. The Elans have a different clutch cover and the bearing on those has a flat surface so they're not interchangeable.
I also picked up these part numbers as well but haven't confirmed them other than the RHP one being listed as equivalent.
Quinton Hazell CCT79 (SKF 413708), AP HD3259 ,RHP 6/W1.5057, FBJ 537018
Brian