I prefer the Festive skin of the Sapper.

Classified ads at the time of posting:

http://m.imgur.com/1rmDooc

http://backpack.tf/classifieds?item=Sapper&quality=11&tradable=1&craftable=1

2*1.31 keys

1*1.35 keys

4*1.37 keys

1*1.4 keys

1*1.5 keys

Unsolds at 1.5 keys:

http://www.tf2outpost.com/trade/27352789 (~3 days)

http://www.tf2outpost.com/trade/27270222 (~2 weeks)

http://www.tf2outpost.com/trade/26979421 (~2 months)

http://www.tf2outpost.com/trade/27365694 (Young)

http://www.tf2outpost.com/trade/27338808 (~5 days)

Unsold at 1 key and 8 refined (~1.5 keys):

http://www.tf2outpost.com/trade/27325581 (~1 week)

Unsolds at Backpack tf price:

http://www.tf2outpost.com/trade/27352634 (~3 days)

http://www.tf2outpost.com/trade/27307827 (~1 week, poorly bumped)

Unsolds at 1 key and 6 refined (~1.4 keys):

http://www.tf2outpost.com/trade/27353997 (~2 days)

http://www.tf2outpost.com/trade/27356408 (~2 days)

http://www.tf2outpost.com/trade/27028601 (~2 months, poorly bumped)

Seller at 1 key and 5 refined (~1.3 keys):

http://www.tf2outpost.com/trade/27349045 (Has 2, ~3 days old)

This is all I could find on Outpost that are valid at the time of posting this suggestion.