slvoid, another piece of advice is to go and try on the glasses you're thinking about ordering for the fit. I'm an Optometrist, but I have no interest selling sunglasses to you. Go mail order! I don't think you can go wrong with either the Native or RP. You get what you pay for in the quality of sunglasses. The variables are in the quality and durability of the construction, the optical quality of the lens, the quality of the optical coating on the lenses, and the replacement policy.

Almost all sunglasses are sufficiently UVA/B blocking, even the 7-11 or Walmart type. "UV blocking" is a natural property of polycarbonate, which is used in almost all sunglasses these days. If they are made of ophthalmic crown glass, such as some of the high end botique glasses like Revo or Maui Jim, they have to have a secondary UV blocking layer. The pupil dilation thing is an urban myth about cheap sunglasses, although I would certainly look for the "100% UVA and B" label on any pair I bought. Even the cheapest lenses have this feature.

As far as Nashbar and Performance brand glasses, I think they make a sacrifice in quality in order to make the price point. If price is an issue, they do offer a good way to protect your eyes from the UV and the other elements. For me, I feel like my vision is worth the extra cost of more expensive glasses. Just my 2 cents.