I can thoroughly recommend Simply Spec, they made up lenses for a pair of RayBan frames I got off the interwebz, and they are outstanding, and I’ve had Oakley Rx lenses before, so I can do a comparison. They do Oakley Rx lenses and frames as well, so well up to scratch. 😉
They also made up another pair of sunglasses using a Bausch & Lombe frame I picked up cheap with badly scratched lenses, and did a fantastic job, cost me £40 because I had multi-layer AR coating, otherwise £20.
http://www.simplyspecs.biz/
I do have an advantage, in that I work just along the road from them, so I can pop in any time, which is handy.