MP sales:

https://marketplace.tf/items/tf2/30978;5;u19

Feb 3: 14.27$ below buy orders

Feb 12: 17.78 / 1.75 = 10 below buy orders

Feb 14: 29.99 / 1.75 = 17

Feb 20, 29: 15.06 at buy order price

March 1: 23.18 / 1.73 = 13 https://backpack.tf/item/7759383917

March 3: 23.18 / 1.68 = 14 https://backpack.tf/item/6877163180

March 23: 15.07 at buy order price

April 12: 22.72 / 1.71 = 13

April 16: 22.72 / 1.78 = 13

Bot.tf sale:

https://bot.tf/stats/item?def=30978&q=5&ef=Circling+Heart&craft=1&aus=0&ks=0

1 @ 12 keys 04/04/2020 Not counting as sold in half a day

Other sales:

1. https://backpack.tf/item/8268577539

https://backpack.tf/profiles/76561198326254870#!/compare/1582502400/1583020800

Unusable

2. https://backpack.tf/item/7759383917

https://backpack.tf/profiles/76561198081458286#!/compare/1583107200/1583280000

Sold for a Circling Heart Vampire Vanquisher = 17

3. https://backpack.tf/item/7190142786

https://backpack.tf/profiles/76561198063456488#!/compare/1584403200/1585526400

Unusable

4. https://backpack.tf/item/6970722563

https://backpack.tf/profiles/76561198097301627#!/compare/1581379200/1581465600

Unusable

5. https://backpack.tf/item/6747249540

https://backpack.tf/profiles/76561198128971451#!/compare/1585872000/1585958400

Unusable

6. https://backpack.tf/item/6747249540

https://backpack.tf/profiles/76561198128971451#!/compare/1585958400/1586044800

Sold for 7 keys. Lower than buy orders

7. https://backpack.tf/item/6747249540

https://backpack.tf/profiles/76561198212488780#!/compare/1585958400/1586044800

Sold for a Dead Presidents Safe'n'Sound. Outdated and no mini possible, not using

Excluding the sales at 17 as sellers at 15 for over a month https://imgur.com/B75qGJ5

Taking 13 - 14 keys