On backpack.tf, it seems as if people are commonly selling this shotgun skin for an average of 2 refined, currently there is 1 sell order for 1.88 refined, 5 sell orders for 2 ref, and 1 sell order for 2.11 ref. There is also a buy order open for 0.77 ref, but it is the only offer for the weapon in buy orders, so it doesn't have much of an effect.

Sell Orders:

https://backpack.tf/classifieds?q=classifieds&item=Shotgun&sort=low&page=2

https://backpack.tf/classifieds?q=classifieds&item=Shotgun&sort=low&page=3

https://backpack.tf/classifieds?q=classifieds&item=Shotgun&sort=low&page=4

Buy Order:

https://backpack.tf/classifieds?q=classifieds&item=Shotgun&sort=low&page=1

Bazzar.tf does not seem to have any set offers for this specific weapon in general, exept for the sell order made 2 months ago by Duke Dugong for 1.8 ref (in the notes)

Duke Dugong's trade:

http://bazaar.tf/profiles/76561198118057692

Finally, on TF2 Outpost, there is one sell order by Tomato that he asks for 2 refined for this weapon, and another sell order by Scarlett were she says to look in her backpack for the price, which says that it costs ~2.01 refined on page 15. Without the set price, in this case there is only one buy order, but it doesn't specify if it is asking for minimal wear or not.

Outpost sell order search:

http://www.tf2outpost.com/search/268999783

Outpost buy order search:

http://www.tf2outpost.com/search/268999973

I am hopeful that, overall, this suggestion does well, as this was probably a very easy decorated item to price, and it could help to get some more diffuclt to price decorated items priced. This could also lead to a page made specifally for the price of decorated items on backpack.tf if decorated item pricing catches on, but for the devolers of backpack.tf, this is just a small added suggestion. :)