So, the mirror arrived today, several days past the 5-day delivery described by their website. The weather sealing is not nearly as clean-looking as the original, and might not seal, but cosmetically it's not too noticeable on a 17-year-old car. I'll probably fiddle with it over the weekend and see whether the factory seals (which are OK) can be made to work. The electric mirror itself works fine.
My verdict: The part's OK, the price was far below the dealer price for the part (more than $200 less even including shipping), but the customer service is terrible (they won't answer the phone, "live chat" takes a while and you have to remind them you're there, and e-mail responses take days), and the delivery time much was longer than I'd expected (10 days vs. 5). Next time I'll find other sources. One can get a comparably priced part from Amazon...