This is my first suggestion, so don't bite me:)

Almost impossible to sell it for the current price.

There are some links:

Sellers:

http://www.tf2outpost.com/trade/7943890 - 2 ref, sold

http://www.tf2outpost.com/trade/7937425 - 2 ref, one sold

http://www.tf2outpost.com/trade/7957799 - 2 ref, unsold

http://www.tf2outpost.com/trade/7932094 - 2 ref, unsold

http://www.tf2outpost.com/trade/7959968 - 2 ref, unsold

http://www.tf2outpost.com/trade/7941473 - 1.66 ref, unsold

Buyers:

http://www.tf2outpost.com/trade/7771653 - 1.33 ref, 3 bought (has 4 in his backpack, but he is the original owner of the 4th rifle)

http://www.tf2outpost.com/trade/7812177 - 1.33 ref, without success

There are a lot of MKII Stranges on the market, but Sniper Rifles has a low demand. 1.33 ref looks like a quicksell price. There are 1.66 ref unsold trade and 2 ref successfully trades, so I guess 1.66 - 2 ref will be a good range.

Edited: Unsold in the current range:

http://www.tf2outpost.com/trade/7877169 - 1 key (3 days unsold)

http://www.tf2outpost.com/trade/7854479 - 1 key (4 days unsold)

http://www.tf2outpost.com/trade/7783231 - 1 key (1 week unsold)

http://www.tf2outpost.com/trade/7932518 - 2.55 ref (1 day unsold)

http://www.tf2outpost.com/trade/7931120 - 2.55 ref (1 day unsold)

http://www.tf2outpost.com/trade/7923239 - 3.33 ref (1 day unsold)

http://www.tf2outpost.com/trade/7773107 - 2.33 ref (1 week unsold)