Holiday headcase buy price on tf2wh is around 3.6 buds sell price, allowing you to immediately buy one from them for less than 4 buds (the former high-range).

No one is buying them for even mid-ranged either, as seen below.

http://www.tf2outpost.com/trade/8504928 (around 3 buds and two bills, so around 3.66 not sold)

http://www.tf2outpost.com/trade/8332622 (same as above)

http://www.tf2outpost.com/trade/8417684 (3.5 buds, has been available for 4 days and no one is buying)

http://forums.sourceop.com/threads/136797-Sandvich-Box%28x3%29-135-Headcase-105-Rare-Stranges (3.5 buds, or $105 cash. Not sold)

http://www.tf2outpost.com/trade/8508895 (roughly 3.33 buds)

http://www.tf2outpost.com/trade/8298347 (3.33 buds, or two for 3.16 buds each, been a week)

http://tf2tp.com/trade.php?trade=9110681 (3 buds and 8 keys, did sell apparently)

http://tf2tp.com/trade.php?trade=9106331 (3 buds pure, sold)

Also, I'm not sure if this counts as proof (first time doing a price suggestion), but in the last week I've bought two headcases for 3 buds from outpost.

http://i.imgur.com/Nnj4pCK.png

http://i.imgur.com/mp5KkRF.png