Surprised no one (successfully) made a suggestion for this yet ^.^

Sold

http://www.tf2outpost.com/trade/12783509 - 1 key + 1 ref

http://www.tf2outpost.com/trade/12781226 - 7.33

http://trade.tf/listings/search/Sell/Unique/Brawling%20Buccaneer/all/2 - Proof its 7.33 for the link above

http://www.tf2outpost.com/trade/12780828 - 1:1 with Hornblower (2-3 keys)

http://www.tf2outpost.com/trade/12780576 - 1 Key + 2 ref

http://www.tf2outpost.com/trade/12780171 - 1 key

http://www.tf2outpost.com/trade/12779060 - 1 key

http://www.tf2outpost.com/trade/12778875 - 1 key + 3 ref

http://www.tf2outpost.com/trade/12778543 - 1 key

http://www.tf2outpost.com/trade/12777601 - 1 key + 2.33

http://www.tf2outpost.com/trade/12775135 - 1 key + 3 ref

http://www.tf2outpost.com/trade/12774907 - 1 key

http://www.tf2outpost.com/trade/12774288 - 2 keys

http://www.tf2outpost.com/trade/12773535 - 1 key + 4 ref (has 3 in his bp, but different histories etc., none which match)

http://www.tf2outpost.com/trade/12772435 - 1:1 with Hornblower (2-3 keys) (Side note: That guys in my friends list xD!)

http://www.tf2outpost.com/trade/12771358 - 1:1 with Hornblower (2-3 keys)

http://www.tf2outpost.com/trade/12767682 - 1 key

http://www.tf2outpost.com/trade/12765137 - 1 key

http://trade.tf/listings/search/Sell/Unique/Brawling%20Buccaneer/all/9 - Proof it sold for 1 key

http://www.tf2outpost.com/trade/12764096 - 2 keys

http://www.tf2outpost.com/trade/12759180 - 2 keys

http://imgur.com/73CKGSP - 1.5 keys

http://www.tf2outpost.com/trade/12758311 - 1:1 with Compatriot (1-1.5 keys)

http://www.tf2outpost.com/trade/12755484 - 1:2 with Founding + 1 ref (6-6.66 ref)

http://www.tf2outpost.com/trade/12754834 - 2 keys

http://www.tf2outpost.com/trade/12754052 - 2 keys

http://www.tf2outpost.com/trade/12752067 - 2 keys

http://trade.tf/listings/search/Sell/Unique/Brawling%20Buccaneer/all/17 - Proof that its 2 keys

http://www.tf2outpost.com/trade/12750674 - 3 keys for Brawl + Compatriot, which makes Brawling 2-2.5 keys

http://www.tf2outpost.com/trade/12750232 - 1 key + 2 ref

http://www.tf2outpost.com/trade/12747194 - 2 keys

http://trade.tf/listings/search/Sell/Unique/Brawling%20Buccaneer/all/19 - Proof thats its 2 keys

http://www.tf2outpost.com/trade/12746899 - 1.9 keys

http://www.tf2outpost.com/trade/12744693 - 1.5 keys

http://bazaar.tf/trade/308157 - 2 keys

http://www.tf2outpost.com/trade/12738812 - 1 key + 1.33

http://www.tf2outpost.com/trade/12738394 - 1 key + 2 rec

http://www.tf2outpost.com/trade/12727900 - 2 keys

http://www.tf2outpost.com/trade/12735749 - 1 key + 2 ref

http://www.tf2outpost.com/trade/12732068 - 2 keys

http://www.tf2outpost.com/trade/12734758 - 1 key + 1 ref

http://www.tf2outpost.com/trade/12734252 - 2 keys

http://www.tf2outpost.com/trade/12734148 - 1 key + 1 ref

http://www.tf2outpost.com/trade/12733737 - 1 key + 2 ref

http://www.tf2outpost.com/trade/12732801 - 2 keys

http://www.tf2outpost.com/trade/12732359 - 1 key + 2.33

http://www.tf2outpost.com/trade/12725812 - 1 key + 2.33

http://www.tf2outpost.com/trade/12725646 - 1 key + 2 ref

http://trade.tf/listings/search/Sell/Unique/Brawling%20Buccaneer/all/29 - Proof its 1 key + 2 ref

http://www.tf2outpost.com/trade/12725442 - 1 key + 1 ref

http://www.tf2outpost.com/trade/12724528 - 1 key + 3 ref

http://www.tf2outpost.com/trade/12723503 - 2 keys

http://trade.tf/listings/search/Sell/Unique/Brawling%20Buccaneer/all/31 - Proof it was 2 keys

http://www.tf2outpost.com/trade/12722307 - 1:1 with Hornblower (2-3 keys)

http://www.tf2outpost.com/trade/12719669 - 1 key + 3 ref

http://www.tf2outpost.com/trade/12718766 - 2 keys

http://www.tf2outpost.com/trade/12718102 - 1 key + 2 ref

http://www.tf2outpost.com/trade/12717832 - 2 keys

http://tf2tp.com/trade.php?trade=9628313 - 2 keys

http://www.tf2outpost.com/trade/12716656 - 2 keys

Conclusion

1 key sells extremely fast, whilst 2 keys is an easy sell by the looks of it. 1 key + 2 ref seems to be the commonly occuring reasonable low-end

1.35 keys = 1 key + 2 ref

Vote accordingly!

Help / Consturctive Criticisim / Additional Proof / Counter-Proof is ALWAYS welcome! :D