So I bought mine for 24 keys, and to be honest I had a lot of sellers to choose from that are selling for 24 keys. I don't want to kick 25 keys out of the range though because there are still sales at that price. Proof below.

Proof

Selling for 24 keys:

http://www.tf2outpost.com/trade/11928469

http://www.tf2outpost.com/trade/11909637 - for 1 bud (23-24)

http://www.tf2outpost.com/trade/11915666 - for 1 bud

http://www.tf2outpost.com/trade/11939575- 24 keys or 1 bud

http://www.tf2outpost.com/trade/11921997

http://tf2tp.com/trade.php?trade=9557111 - for a bud

http://tf2tp.com/trade.php?trade=9555589

http://tf2tp.com/trade.php?trade=9554698 - sold

http://backpack.tf/classifieds/search/strange%20festive%20sticky - also a few being sold in the classifieds for 24 keys or a bud from time to time. (sorry for weird link)

Sold for 25 keys:

http://tf2tp.com/trade.php?trade=9541053

Less than 24:

http://www.tf2outpost.com/trade/11914240 - 23 keys

http://www.tf2outpost.com/trade/11703534 - 22 keys

As you can see there are many selling for 24 keys, and less for 25 now, with the odd exception of lower.

Proof of me buying mine for 24 keys: http://i.imgur.com/b3BHLzj.jpg

Anyway, this is all I've got so far, if you have any queries or questions or suggestions please post below.

Thanks.