Counter, definitely shouldn't drop that low.

Sale 1:

http://backpack.tf/profiles/76561198125086452#!/compare/1475625600/1475712000 Sold for a Phos Slouch (38 keys) and a DBD Firewall (21 keys)

Slouch mini

http://backpack.tf/profiles/76561198199148330#!/compare/1473552000/1474070400

Sold for an aussie ambi (15 keys), a ks aussie flamethrower (15 keys), and 8 keys. (the aussie sniper and the kit were unrelated to the trade, look at the histories) taking 38

Firewall mini:

http://backpack.tf/profiles/76561198138873761#!/compare/1468800000/1468972800 25 pure

http://www.tf2outpost.com/trade/28547766 seller at 21 for 8 hours, young, but I think it's overpriced anyways and the first sale is a day from being outdated, so i'm taking 21 on the firewall

59 keys. Pretty sure there was a buyout, but I can't find solid evidence on that. Seller didn't have an outpost trade on it. Rounding to 60.

Thanks to ghost soldier for sale 2:

Sale 2:

http://backpack.tf/profiles/76561198162848836#!/compare/1475539200/1475625600 Sold for an aussie rocket launcher.

Thanks spotlight for pointing out:

http://www.tf2outpost.com/trade/28151435

5 month unsold at 55.

Capping the high end at 55