I've had good results with the cheap online eyeglasses for simple single focus Rx types like for a computer reading pair or distance only with tint for Rx sunglasses. But the cheaper sites progressive pairs were low quality compared to from a local optometrist and whatever lab they used. I did last year order a better quality progressive pair from a more upscale online site (eyeglasses.com) that uses a good lab and can set the segment height properly, that pair works well for me, with kinda in between price between the cheap online sites vs a local optometrist.
Oops, the good progressive pair I bought last year wasn't from eyeglasses.com it was from FramesDirect.com which uses a USA lab near them in Texas i believe.
They claim: "As a company founded by doctors, FramesDirect.com sells nothing but the absolute best lenses available on the market today. The Essilor digital progressive lens delivers effortless vision in a full back-sided, digitally surfaced lens design"
Thats what interested me to trying them after the poor quality from the China-made cheaper progressive pairs I tried first.