All are clean of parts/spells/killstreaks

Sellers:

http://www.tf2outpost.com/trade/23411483 3 ref "bp price" (unbumped)

http://www.tf2outpost.com/trade/23364091 3 ref "bp price" (poorly bumped)

http://www.tf2outpost.com/trade/20897575 3 ref (has multiple, months old, sold a few)

http://www.tf2outpost.com/trade/23424961 ~3 ref "around backpack price" (12 hours old from creation to last bump)

http://www.tf2outpost.com/trade/23359564 3.33 ref (poorly bumped)

http://www.tf2outpost.com/trade/23428261 4 ref (13 hours old, unbumped)

http://www.tf2outpost.com/trade/23393409 4.33 ref (2 days old)

http://www.tf2outpost.com/trade/22905199 6.33 ref (month old, priv bp)

http://www.tf2outpost.com/trade/23430194 8 ref (8 hours old, unbumped)

http://www.tf2outpost.com/trade/23300127 "offers" (poorly bumped?)

http://www.tf2outpost.com/trade/23412774 "selling two strange items for 2 keys" (unbumped)

Sold:

http://www.tf2outpost.com/trade/23391547 <1 hour 2 ref (S. Escape + S. RL for 4 ref)

http://www.tf2outpost.com/trade/23402008 <3 hours 3 ref

http://www.tf2outpost.com/trade/23272557 <3 days 3 ref

http://www.tf2outpost.com/trade/23318706 <30 hours 3 ref

http://www.tf2outpost.com/trade/23437268 <1 hour 3 ref

http://www.tf2outpost.com/trade/23437067 <3 hours 2x 3 ref

http://www.tf2outpost.com/trade/23403274 <1 hour 3 ref

http://www.tf2outpost.com/trade/23427051 <4 hours 3 ref

http://www.tf2outpost.com/trade/23426714 <3 hours 3 ref

http://www.tf2outpost.com/trade/23417387 <1 hour 3 ref

http://www.tf2outpost.com/trade/23411404 <1 hour 3 ref

http://www.tf2outpost.com/trade/23410734 <24 hours 3 ref

http://www.tf2outpost.com/trade/23426264 <1 hour 3.22 ref

http://www.tf2outpost.com/trade/23407606 <24 hours 3.33 ref

http://www.tf2outpost.com/trade/23414579 <24 hours 3.33 ref

http://www.tf2outpost.com/trade/23418646 <1 hour 3.66 ref WITH squash rockets spell

http://www.tf2outpost.com/trade/23411678 <2 hours 3.88 ref

http://www.tf2outpost.com/trade/23432814 <5 hours 4 ref

http://www.tf2outpost.com/trade/23405040 <2 hours 4 ref

http://www.tf2outpost.com/trade/23416118 <3 hours 4 ref unconfirmed sale (priv bp)

http://www.tf2outpost.com/trade/23225599 <10 days 4 ref

http://www.tf2outpost.com/trade/23367280 <3 days 4.33 ref

http://www.tf2outpost.com/trade/23154801 2 weeks 6 ref each, sold 2

1x 2 ref, 12x 3 ref, 1x 3.22, 2x 3.33, 1x 3.66, 1x 3.88, 4x 4, 1x 4.33, 2x 6

http://www.tf2outpost.com/trade/23399036 <48 hours "offers"

http://www.tf2outpost.com/trade/22901313 unknown sale

http://www.tf2outpost.com/trade/23408251 unknown sale

http://www.tf2outpost.com/trade/23402183 <48 hours "offers"

Classifieds, 7:28 PM EST 10/30/2014:

2x 4 ref

1x 5.33

All others, parts attached/killstreak

Scrap.tf:

1x 3.22 http://i.imgur.com/1BdiS7i.png

Conclusion: While 3 ref seems to quicksell, there are still many sales at 3 ref. Sales occur at 4 ref and between 3-4 ref, and taper off greatly past 4 ref. Thus 3-4 ref.