1 year old price

Credits to [TH] Muselk for the info

Credits to wolfilicious and Leo [↯] for the sales and minis from another suggestion.

1st sale, 3 months old:

http://www.tf2outpost.com/trade/24214587

Sold for Stare hermes(40keys) + PS attendant(80 keys)+ bubbling company(27 keys)+ 1 bud(13 keys).

Minis:

PS attendant: sold for an anti freeze head warmer (80 keys, average)

Before:backpack.tf/profiles/76561198100334597?time=1424073600

After: backpack.tf/profiles/76561198100334597?time=1424246400

Total: 146 keys

After overpay= 146*0.9=131 keys

Sale #2: 15 days ago, super super recent(most).

Used with a Bliz Front runner (23 keys, average) to buy a sunbeams swagman's swatter (135 keys, average)

Before: https://backpack.tf/profiles/76561198101704125?time=1429686000

After: https://backpack.tf/profiles/76561198101704125?time=1429858800

No need for minis, both recent prices, so yeah.

Total-> 135-23= 112 keys

After overpay=0.9*112= 100 keys

Sale #3 (Completely an outlier. Been sold for much lower, and more recent as well, so there is no reason for it to be priced too high)

http://www.tf2outpost.com/trade/25619474

Used with a duped scorching dragonborn(132, recent) + duped ghost modest(82, recent) to buy a screaming tiger conga (480 keys, recent)

No need for minis, all recent prices.

480-82-132= 266 keys

Like I said, this is an outlier sale, so this cannot be used.

So, in the end, average-> (100+131)/2 = 115 keys