I got a suggestion to suggest 22-25 instead of 21-25, so here we go:

Just because I own one does not mean I am trying to raise the price of my own backpack.

Here are the few on outpost:

http://www.tf2outpost.com/trade/9623578 - I bought this one for 24 keys plus 1.5 keys in sweets. He was previously offered 27 keys, 1 bud and 2 keys (26.5 keys), a SF sniper with headshots (25 keys), 19 keys and a pink bill's (28 keys), and a few unusuals

http://www.tf2outpost.com/trade/11045490 - B/O of 28 keys, no offers yet

http://www.tf2outpost.com/trade/11213926 - Offered him 25 keys and he wouldn't take it

http://www.tf2outpost.com/trade/10749987 - Offered a steaming pot, blizzardy storm larrikin (21-25 keys)

http://www.tf2outpost.com/trade/10258607- Sold for 22 keys, which was 1 bud back then

http://www.tf2pricecheck.net/Thread-PC-Orbiting-Planets-Stainless-Pot?page=2 - current price of 25 keys or 1 bud

I will work on more proof as offers come in. Any help would be appreciated.

The suggestion for the new price range was from here: http://backpack.tf/vote/id/51b39a6a4bd7b80e2600000e