http://www.tf2outpost.com/trade/11933846 - 19 keys

http://www.tf2outpost.com/trade/10914151 - Selling for 20 keys, ended up adding 4-5 (?) keys for a sf knife. Not counting overpay (as sf knife was an item in the wishlist the hotrod sold for ~18)

http://www.tf2outpost.com/trade/12162948 - idk how this trade works, but his/her min bid is 15 keys

http://www.tf2outpost.com/trade/11664775 - Selling for 20 keys for 2 weeks. Offer of 18.

http://www.tf2outpost.com/trade/10085040 - Offer of Orb. Fire Prancer's (w/ overpay ~18 keys)

http://www.tf2outpost.com/trade/11713225 - Selling for 20 keys for 2 weeks. 1 person willing to pay 20 but then seemingly bought something else

http://www.tf2outpost.com/trade/10456987 - Blizz Hotrod if he/she adds 5 keys (~17.5 w/ overpay but they were looking to upgrade so overpay doesn't really apply. ~20 keys w/out overpay)

http://www.tf2outpost.com/trade/11619408 - Sold for 18 keys

http://www.tf2outpost.com/trade/11801118 - Only offer in a week is 17 keys

http://puu.sh/3qJsD.png - 18 keys

Most seem to sell for about 18 keys but a range is still necessary as there are some sales/offers above that, but none at 21 keys which is within the current range.