http://www.tf2outpost.com/trade/22868709 - offered 18 and 19 keys recently and 20 keys about a month ago

This seems low. Just speaking from experience on my of noir. I had 4 people offer me 1-1.1 pure in 2 days. And blizz usually is considered higher. Sure enough, when you look at the trades, they are getting pure offers higher than 1-1.2

1. http://www.tf2outpost.com/trade/24980391 Sold for 16 keys pure ( ~1.3 buds) Backpack of seller after the trade http://backpack.tf/profiles/76561198051206974?time=1423468800

2. http://www.tf2outpost.com/trade/24454169 Sold for 16 keys pure (~1.1 buds at the time)

Backpack of seller after the trade

http://backpack.tf/profiles/76561198044186719?time=1420617600

3. http://www.tf2outpost.com/trade/23889042 Sold for 18 keys pure (~1.4 buds at the time of the sale. )

Backpack of seller after the trade

http://backpack.tf/profiles/76561198108299696?time=1419840000

4. http://www.tf2outpost.com/trade/24941863 Sold for 16 keys pure(~1.3 buds)

Backpack of seller after the trade

http://backpack.tf/profiles/76561198050890619?time=1423641600

5. http://www.tf2outpost.com/trade/24554770 Sold for Dead Presidents Hottie's Hoodie ( ~1.65 buds * 0.9 = ~1.5 buds) + Sweets but cap at b/o of 1.5 buds.

Backpack of seller after the trade.

http://backpack.tf/profiles/76561198076054239?time=1420986718

With all these sales, your range is low here. I would probably go with a 1-1.5 buds range here. This range might even be low here considering the frequency of pure sales at ~1.3 buds but can't really ignore the b/o of 1 bud + 3 keys(~1.2 buds) for 5 days from your first sale.