Counter - Re-done with more proof, all research by myself, taking risk on this one :/

http://goo.gl/Neh94h - None on Classifieds at 2 keys. One at 1.47 (Rounding up to 1.5), Two at 1.58 (Rounding up to 1.6), SEVEN at 1.7

http://www.tf2outpost.com/trade/21289077 (1.5 keys ~ apparently sold)

http://www.tf2outpost.com/trade/21307955 (1 key 5 refs ~ 1.6) 4 hours, unbumped

http://www.tf2outpost.com/trade/21311108 (1 key 5 refs ~ 1.6) 1 hour young, unbumped

http://www.tf2outpost.com/trade/21307955 (1 key 5 refs ~ 1.6) 4 hours, unbumped

http://www.tf2outpost.com/trade/21305038 (1 key 5 refs ~ 1.6) 6 hours young, bumped

http://www.tf2outpost.com/trade/21293493 (1 key 5 refs ~ 1.6) 17 hours, poorly bumped

http://www.tf2outpost.com/trade/21301165 (1 key 6 refs ~ 1.7) 9 hours young, bumped

http://www.tf2outpost.com/trade/21299382 (W>1.7) 11 hours young, poorly bumped)

http://www.tf2outpost.com/trade/21301405 (1 key 6 refs ~ 1.7) 9 hours, unbumped

http://www.tf2outpost.com/trade/21297594 (1 key 6 refs ~ 1.7) 12 hours young, bumped

http://www.tf2outpost.com/trade/21284568 [same guy as classifieds](1 key, 6 refs ~ 1.7) 1 day, autobump

http://www.tf2outpost.com/trade/21247091 (1 key 6 refs ~ 1.7) 2 days, unbumped

http://www.tf2outpost.com/trade/21244343 (1 key 6 refs [Sold] ~ 1.7) 2 days, bumped

http://www.tf2outpost.com/trade/21209594 (1 key 6 refs ~ 1.7) 4 days, bumped

http://www.tf2outpost.com/trade/21270287 (1 key 6.33 refs ~ 1.73) 1 day old, bumped

http://www.tf2outpost.com/trade/21281007 (1 key 6.33 refs[3-in-stock] ~ 1.73) 1 day old, bumped

http://www.tf2outpost.com/trade/21138213 (1 key 6.66 refs ~ 1.75) 6 days, poorly bumped

http://www.tf2outpost.com/trade/21309524 (1 key 7 refs ~ 1.8) 2 hours young, bumped

http://www.tf2outpost.com/trade/21305387 (1 key 7 refs ~ 1.8) 6 hours young, unbumped

http://www.tf2outpost.com/trade/21290844 (1 key 7 refs ~ 1.8) 20 hours, bumped

http://www.tf2outpost.com/trade/21282499 (1 key 7 refs ~ 1.8) 1 day, unbumped

http://www.tf2outpost.com/trade/21285138 (1 key 7 refs ~ 1.8) 1 day, bumped

http://www.tf2outpost.com/trade/21208439 (W>1.8) 4 days, poorly bumped

http://www.tf2outpost.com/trade/20984113 (W>1.8!?) 1 week, poorly bumped

http://www.tf2outpost.com/trade/21303574 (1 key 7.33 refs ~ 1.8-1.83) 7 hours, bumped

http://www.tf2outpost.com/trade/21189873 (1 key 7.33 refs ~ 1.8-1.83) 4 days, bumped

http://www.tf2outpost.com/trade/21239405 (1 key 7.55 refs ~ 1.85) 2 days, poorly bumped

http://www.tf2outpost.com/trade/21308048 (1 key 8 refs ~ 1.9) 4 hours, unbumped

Why 2 keys is still in range? Cos it still can sell, proof:

http://www.tf2outpost.com/trade/21247910 (Sold for a G. Double cross com[3.5], he added a key)

http://www.tf2outpost.com/trade/21133294 (Sold for 2 keys) still selling one.

http://www.tf2outpost.com/trade/20971618 (Claims that have sold many at 2 keys from that post)

Two dudes from the other suggestion claim have sold for 2 keys easily.

http://prntscr.com/43shy5

http://prntscr.com/43si52

Final Conclusion

With one seller at 1.5, five sellers at 1.6, Eighteen at 1.7(including mass sellers), Eleven between 1.7 and 2, and proved that 2 can still sell, a range of 1.7-2 would be the best for now, in my opinion.

Helpful links, counterproof, advice, love and hatred more than welcome, have a great weekend!