https://marketplace.tf/items/tf2/617;5;u45

August 8 - $299 = 164 keys https://backpack.tf/item/2048288041

September 6 - $333.33 = 183 keys https://backpack.tf/item/2048288041

https://backpack.tf/profiles/76561198252999692#!/compare/1565827200/1565913600

https://backpack.tf/profiles/76561198280357510#!/compare/1565827200/1565913600

Sold with 57 keys for Flies Pyromancer's Mask and Green Energy Yellow Belt

Flies Pyromancer's open suggestion at ~38.5 keys https://backpack.tf/suggestion/5d65f8ecd381723374534871

Green Energy Yellow Belt open suggestion at ~177.5 keys https://backpack.tf/suggestion/5d6d7b77d38172738f64c1a2

This makes the Harvest Moon Ballcap ~159 keys.

https://backpack.tf/profiles/76561198101185527#!/compare/1565481600/1566432000

https://backpack.tf/profiles/76561198280357510#!/compare/1566345600/1566432000

Sold with Aces High Dragonborn Helmet for Arcana Familiar Fez

Using there

https://backpack.tf/profiles/76561198106511423#!/compare/1567555200/1567641600

https://backpack.tf/profiles/76561198080706417#!/compare/1567468800/1567641600

Added Ominous Night Shred Alert for Burning Defragmenting Hat

https://backpack.tf/suggestion/5d6fed46d3817279ad6863e3 Burning Defragmenting being updated to 200 keys

Shred Alert in-date at ~24.5 keys https://backpack.tf/suggestion/5d59a508678072344b740a35

Taking this as 176 keys

However, after this trade, the user put the Ballcap back up for sale at 170 keys.

Current sellers:

https://gyazo.com/f88deba2994dc00531a2566998ced680

170 keys - 22 days - duped

170 keys - 3 days - from the Burning Defrag. Hat sale

200 keys - 8 days - from the Sept. 6 Marketplace sale

Sales:

159 keys

164 keys

176 keys

183 keys

Going with 160-170 keys, capping the high end at the current clean seller.