Such as, you have a pair of these glasses which you find acceptable?
I do take your previous text as an affirmative, but would like concrete
confirmation -- I know the money is small, which is at risk, still I don't
like being "stiffed."

One of the problems in getting a good fit is determining the optical center
of your eyes. Just because a particular frame fits two people well, that
doesn't mean their eyes are in the same positions relative to the frames. If
all you need is simple dioptric correction, this might not matter, but if
correction for astigmatism is required, you want the lens "centered" over
the eye.

An optician puts a gadget over your eyes that lets them determine where the
pupils fall. The lenses are then ground with their optical centers at those
points.

For this reason, I would not have a Web or overseas company grind the
lenses. Costco should be cheap enough.