If you live in the Seattle area, it's worth a visit to the Amazon Bookstore at University Village if you've been trying to find one of these. I was just there to grab one. They had at least 50 behind the counter.
Not sure of stock at Amazon Bookstores in other cities.
Update - I'm hearing that the Bellevue, WA has stock too. Still unsure of stock at stores outside Amazon's home market.
Update 2 - Didn't get the other SNES classic at the Amazon Bookstore thread in my initial search before posting. Abandoning this thread and taking chat over there.