Try EyeQ optician in Millburn - he replaces my lenses in existing frames.
Dawn's opticians in South Orange does lenses only. We brought Lego frames from the UK and she put the lenses in.
The optician in Sally Bregman's office has done this for me -- I have reading glasses made from old frames.
Costco! My savings on eyeglasses there covered several years of the membership fee. They will inspect your frames and provide lenses only provided they are deemed in good condition. (Mine were.) They also have a selection of frames and my husband found some he liked.
I did end up at Costco! Thank you all... They were surprisingly well staffed with at least 6 sales people working very hard in the optical area. I "splurged" for the $120 top-of-the-line lenses and feel like I have not been taken advantage of in any way at all.
I have the frames. I have the prescription. I only need single-vision lenses . Suggestions?