Taking Mindacos' advice and going with 48-55.

Sale 1

Sold for 70 keys.

http://backpack.tf/profiles/76561198134333889#!/compare/1469404800/1469491200

http://www.tf2outpost.com/trade/28347730 ----- B/O was 72 keys (sold quickly)

=======> 70 keys

======================================================

Sale 2

Sold with a Cool WW SKS Woodsy SMG for a Bonzo Harmburg.

http://backpack.tf/profiles/76561198157356020#!/compare/1469750400/1469836800

Using this for the Harmburg.

=======> Not using

======================================================

Sale 3

Sold for 55 keys

http://backpack.tf/profiles/76561198081172172#!/compare/1471996800/1472083200 (sort by time)

http://www.tf2outpost.com/trade/28378594 ----- B/O was 62 keys. Buyer offered there (took ~4 weeks to sell)

=======> 55 keys

======================================================

Sale 4

Sold for a Stormy Veil + ~4 keys

http://backpack.tf/profiles/76561198115721685#!/compare/1471651200/1471737600

http://www.tf2outpost.com/trade/28432883 ----- B/O was 60

Could be used for the Veil.

=======> Not using

======================================================

Sale 5

Sold for 48 keys

http://backpack.tf/profiles/76561198070635520#!/compare/1471564800/1471651200 (sort by time)

http://www.tf2outpost.com/trade/28427927 ----- B/O was 55 keys, took more than a week to sell (was relisted from here: http://www.tf2outpost.com/trade/28410566 )

=======> 48 keys

======================================================

Sellers

- http://www.tf2outpost.com/trade/28180239 ----- No B/O, but rejected 70 pure from the guy from sale 1.

- http://www.tf2outpost.com/trade/28433713 ----- 65 keys

Summary

- Sales for 48, 55 and 70 (all pure).

Going with 48-55 keys. 70 might be an outlier here given B/Os for lower and unused sales (Veil and Harmburg). The guy from sale one was willing to overpay judging by the other offer on that Outpost trade (credits to Mindacos :) ).

Criticism appreciated!