Having a brief study of economics, I can say that there probably is not a huge warehouse of 770s.

Reasons:

It was a experiment by Nokia. They did not expect the # of sales they got. So, my bet is that they were made in small batches. This means supply into the warehouse was either a little higher or equal to the supply out, so very little shelf life.

Its hella old, so holding 770s in a warehouse (if there was one) would be very expensive. Think about it, there are no more new 770s, and almost no one is buying them. They are not covered under warranty anymore, etc.. No one is going to buy them from the warehouse (aside from you, moshing, who the warehouse owners did not predict), so it might be more cost effective to actually destroy the 770s and free up shelf space for them iPhones. Take a hit in the short-run, and profit in the long.

Hope you find it though...