In dire need of an update.

Sale 1:

https://backpack.tf/profiles/76561198410975747#!/compare/1505347200/1505520000

Sold for a Vivid Plasma Officer's Ushanka + 3 keys. Can't find a suitable mini for the Ushanka, so I'm not going to use this.

Sale 2:

https://backpack.tf/profiles/76561198342398717#!/compare/1505865600/1506038400

Sold for 28 keys. But it looks like it was sold to a quickbuyer who has a buy order for 28 keys right now.

Sale 3:

https://i.imgur.com/56ij6Gh.png

Sold for 33 keys. Doesn't look like a quicksell from backpack histories. Using as low end.

Sale 4:

https://i.imgur.com/V6Q9ypL.png

https://backpack.tf/item/6107290521

https://backpack.tf/item/4689777691

Sold for Phosphorus Armored Authority, then traded back along with 2 keys. I don't know how to factor in tradebacks for suggestions, so I'll leave this here, and re-suggest if needed.

Sale 5:

https://backpack.tf/profiles/76561198208062409#!/compare/1512000000/1512086400

Sold with 10 keys for a duped Purple Confetti Soldier's Stash.

Stash Mini:

https://i.imgur.com/n3duss3.png

http://www.tf2outpost.com/trade/29463046

Sold for 30 keys + Circling Heart Bomb Beanie. Beanie is in date but capped by B/O at 45. This puts the Helm sale at 35 keys.

Sale 6:

https://backpack.tf/profiles/76561198190592661#!/compare/1505779200/1506038400

Sold with 7 keys for a Starstorm Insomnia Salty Dog. Each key matches the history of the Helm, I checked. Dog is not in date so here's a mini:

https://backpack.tf/profiles/76561198112509663#!/compare/1506470400/1506556800

Sold for 11 keys and a KaW Well Rounded Rifleman, putting it at 52 keys. This values the helm at 45 keys. Using for high end.

Sale 7:

https://backpack.tf/profiles/76561198015384426#!/compare/1511308800/1511395200

http://www.tf2outpost.com/trade/29446804

Sold for 35 keys pure, I think. If anyone involved in the trade could come forwards and verify that would be great.

Sale 8:

https://backpack.tf/profiles/76561198081875069#!/compare/1511654400/1512259200

Sold for a It's a puzzle to me Death Racer's Helmet. Helmet is out of date and I can't find a mini, but this would probably be around 45ish. If someone has a suitable mini I would appreciate it.

So that's all the sales I could find. There are lots of holes in the histories and I could find minis for some of them, so I'm not completely satisfied.Feel free to correct me if I did anything wrong in the comments!