If you were wearing contacts or had a simple prescription, then yes, I'd consider ordering online. But in your case, I'd spend the money to get the right pair. Just be sure to bring someone you trust to help choose the frames.
His last pair was $650.
Thanks for that advice, Kathryn. In fact my new glasses are very stylish (they're Georgio Armani frames, so they'd better be!) and that's part of the reason I'm not very happy with them: I am an anti-stylish person. I find they make me look like a Manhattan advertising executive or some trying-to-be-hip-but-over-the-hill urban radio announcer (in fact they make me look like a very specific urban radio announcer here in my city, and a couple of people have stopped me on the street, thinking I was that guy). The problem is that I am not a hip urban kind of person, so it's an image that I have a hard time reconciling with myself.
The two people who helped me pick them out were the woman at the eyeglass shop and my girlfriend, and they were unanimous that these glasses looked great on me, so I trusted them. I am starting to get used to these new specs, but when I first got them with the prescription lenses and saw what I looked like with them on, my reaction was "what were they thinking?" Of course the woman at the eyeglass center was thinking, "I'm going to sell this gullible fellow some really expensive frames and I'll get a nice commission," but I was surprised that my girlfriend also thought they were right for me. In the end, though, the women in my life have usually turned out to be right about these kinds of things and I may very well grow to like them.
My main worry is that these glasses will lead me down a slippery slope toward becoming more stylish, because right now most of the clothes in my wardrobe are between 10 and 20 years old and not very snappy. Will I have to buy a new suit to go with my new glasses? Maybe a cool black and grey striped shirt? Expensive shoes? Brooks Brothers socks? It all horrifies me a little

I've succesfully avoided paying any attention to style for all my adult life...I'm 50 years old and I don't really want to start now.
But I'll keep the glasses.