A couple of my (adult) children have used Zenni Optical. I ordered progressive-lens sunglasses. Wow. The frame a top quality. The prescription is spot-on perfect. And the cost - well, that's the wow. Less than 1/3 what pretty much identical glasses would have cost if bought through my local "vision center."
I've used B&H on and off for years. Never been disappointed. Remarkable depth and variety of electronics. The free shipping and no state sales tax for purchases outside New York, when combined with their already-low prices, makes this a top choice for electronics of every kind.