Seeing a pair of glasses superimposed over a photo of your face is not the same as trying them on. Sure, it's a good start, and yeah, a lot of online options let you order multiple pairs and then you return the ones you don't want, but I've never tried it because every time I get new glasses, I have to try on more than 5 pairs, usually a lot more than 5 pairs. It's difficult for me to find a good and comfortable fit, because oddly enough, different humans have different head shapes. Who knew?
I agree, skyrefuge, fit is a combination of frames + face, and shouldn't have anything to do with price. In my experience the price is irrelevant to how it fits my face.
I wear contacts most of the time and I've had my current glasses for 4 years even though the prescription needs to be updated; I'm not a daily wearer, just nights/weekends. They were originally ~$250 (total, including lenses) and they're in much better shape after 4 years than, say, the $30 pair I had when I was 15, which I kept having to get fixed.
Glasses are in an odd category, I think. Technically, they're an assistive device; just because we as a culture have also decided they're an accessory doesn't mean we need to solely consider them as such when we, the wearers, are obtaining them. Purchasing glasses does not have the same considerations as a handbag, because I need glasses to, um, SEE. And yeah, quality is a thing. Avoiding 'designer' frames is going to limit your available options just as surely as avoiding cheap frames will, and I'd rather not limit myself when choosing an assistive device.
So my point, there are a lot of things to consider when choosing glasses, and they all have to be weighed, and how we weigh those is an personal decision. The fact that glasses have become an accessory has muddied the waters and requires more effort to be frugal in this area.