I own a few of these, but that evidence looks pretty convincing. Upvoted.

Apart from people selling all their stuff to get keys to uncrate, I guess another reason the price has gone down is that people tend to open more of the recent crates (41-49), which contain these, so more are coming onto the market and being quicksold.

Here's one more, selling for 2 keys :/

http://www.tf2outpost.com/trade/5966332

Downvote. Sold a few of these in the past few days for 3 keys each.

@Age of Crates

3 Keys is still within the range. I couldn't sell mine for 3 keys the last days.... --> Upvote

I've bought some for less than 3 keys in the past few days; upvoted.