Got this on my second Mecha tour.

Classified ads at the time of posting:

Page 1 - http://m.imgur.com/4NpMztZ

Page 2 - http://m.imgur.com/ODMharv

Page 3 - http://m.imgur.com/nHZCV9r

http://backpack.tf/classifieds?item=Silver+Botkiller+Minigun+Mk.II&quality=11&tradable=1&craftable=1

1*2.55 refined

1*3.55 refined

4*4 refined

5*4.33 refined (2 have a part attached)

1*4.55 refined

12*4.66 refined

Unsolds at 4.66 refined:

http://www.tf2outpost.com/trade/27402802 (~4 days)

http://www.tf2outpost.com/trade/27415905 (~1 day, young)

http://www.tf2outpost.com/trade/27359384 (~1 week)

http://www.tf2outpost.com/trade/27400157 (~4 days)

http://www.tf2outpost.com/trade/26479213 (~4 months)

http://www.tf2outpost.com/trade/27422894 (Young)

http://www.tf2outpost.com/trade/27369799 (~1 week)

http://www.tf2outpost.com/trade/27408710 (~2 days)

http://www.tf2outpost.com/trade/27372886 (~1 week)

http://www.tf2outpost.com/trade/26585009 (~3 months)

http://www.tf2outpost.com/trade/27420578 (Young)

http://www.tf2outpost.com/trade/27377037 (~1 week, poorly bumped)

http://www.tf2outpost.com/trade/27356766(~1 week, poorly bumped)

http://www.tf2outpost.com/trade/26751450 (~3 months, poorly bumped)

http://www.tf2outpost.com/trade/27399878 (~4 days, never bumped)

Unsold at 4.55 refined:

http://www.tf2outpost.com/trade/27380992 (~1 week, never bumped)

Unsold at 4.5 refined:

http://www.tf2outpost.com/trade/27263657 (~3 weeks, poorly bumped)

Unsold at 4.44 refined:

http://www.tf2outpost.com/trade/26776364 (~3 months, poorly bumped)

Unsold at 4.33 refined:

http://www.tf2outpost.com/trade/27410767 (~2 days)

Unsold at 4.22 refined:

http://www.tf2outpost.com/trade/27415999 (~1 day, young)

Sellers at 4 refined:

http://www.tf2outpost.com/trade/27417623 (~1 day old)

http://www.tf2outpost.com/trade/27386433 (~6 days old, never bumped)

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