Idk man, there is a huge difference between even regular OP frames and the MP-2 ones (from the MIJ vintage line) that my sunglasses are. Even the lenses are leagues ahead of the standard ones they put in their regular sunglasses. The Thom Browne frames he posted are made by Dita and indeed are really nice, just not $700 nice (which is why I got the $500 OP instead of a similar TB model) I looked at a LOT of sunglasses before settling on these and it's the same story we have with our clothes. It's not just the materials and construction but certain attention to detail, but there are noticeable differences in all 3 between some $300 Luxotica manufactured thing and something mid-tier (500-800) we're discussing here. Go even more extreme and compare these these to something like Warby Parker and you'll be blown away at the difference.
sunglasses and eyeglasses are two different categories, because with eyeglasses the lens quality is dictated by your optometrist not the brand itself. what we're really talking about when it comes to eyeglasses is frame quality, and there's really little difference between warby parker and oliver peoples MIJ preluxxotica -- I own both. the warby parkers are a little flimsier, but not enough to justify the $600 price difference.
also you know OP is owned by luxxotica right?
i could maybe see paying $700 for some MTM glasses or something out of real tortoiseshell, but other than that no way.
as far as sunglasses quality goes, you should check out randolph engineering. IME better quality than any of the luxe lines.