This is a conservative suggestion for now. It can be refined later.

No serious buyer trades.

Classifieds have a couple at 3 ref and a few at 4 ref: http://backpack.tf/classifieds/search/30053/6/0

Offers

http://www.tf2outpost.com/trade/10941853 Couple rejected 3 ref offers

http://www.tf2outpost.com/trade/10908110 3 ref

http://www.tf2outpost.com/trade/10973347 3 ref

http://www.tf2outpost.com/trade/11000535 3 ref

http://www.tf2outpost.com/trade/11014636 3 ref

http://www.tf2outpost.com/trade/10970218 3.33 ref

http://www.tf2outpost.com/trade/10964462 3.44 ref

http://www.tf2outpost.com/trade/11009842 3.5 ref

http://www.tf2outpost.com/trade/10977791 4 ref

http://www.tf2outpost.com/trade/10985681 4 ref

http://www.tf2outpost.com/trade/10915253 4.33 ref

http://www.tf2outpost.com/trade/10877475 4 ref, 1 key, WW Wrap

Sold

http://www.tf2outpost.com/trade/11033792 2 ref

http://www.tf2outpost.com/trade/11000535 3 ref

http://www.tf2outpost.com/trade/11032439 3 ref

http://www.tf2outpost.com/trade/11003108 3 ref

Sellers:

http://www.tf2outpost.com/trade/11040108 2.88 ref

http://www.tf2outpost.com/trade/10968135 3 ref (Spreadsheet)

http://www.tf2outpost.com/trade/10984138 3 ref

http://www.tf2outpost.com/trade/11005552 3 ref

http://www.tf2outpost.com/trade/11033083 3 ref

http://www.tf2outpost.com/trade/10985731 4 ref

http://www.tf2outpost.com/trade/10990261 4 ref

http://www.tf2outpost.com/trade/11015227 4 ref

http://www.tf2outpost.com/trade/11025951 4 ref

http://www.tf2outpost.com/trade/11028129 4 ref

http://www.tf2outpost.com/trade/11041042 4 ref

http://www.tf2outpost.com/trade/10982610 5 ref

http://www.tf2outpost.com/trade/10908110 1 key, willing to go 4 ref

http://www.tf2outpost.com/trade/10897902 1 key, 3 days

http://www.tf2outpost.com/trade/10898454 1 key, 3 days

http://www.tf2outpost.com/trade/10975328 1 key, 2 days

http://www.tf2outpost.com/trade/10996883 1 key, 1 day

http://www.tf2outpost.com/trade/11003450 1 key, 1 day (110 views)

http://www.tf2outpost.com/trade/11004853 1 key, 1 day

tf2spreadsheet.traderempire.com has it at 3 ref