My first unusual suggestion, constructive criticism is welcomed.

Sale #1

Sold for 38 keys? The seller's backpack wasn't updated very frequently so I couldn't see a time where the Ground Control was actually in his inventory. There was also no posts on the outpost trade: http://www.tf2outpost.com/trade/26869131

The only evidence of a sale was here when his backpack gained 38 keys: http://backpack.tf/profiles/76561198020172660?time=1439449200

I don't know if I can use this in the range as I don't know if the keys were actually from the sale of the Ground Control.

Sale #2

Sold for 30 keys pure: http://www.tf2outpost.com/trade/26845520

Backpack of the seller before trade: http://backpack.tf/profiles/76561198219681600?time=1440226800

Backpack after trade: http://backpack.tf/profiles/76561198219681600?time=1440313200

Sale #3

Sold for 32 keys and 3 keys in sweets: http://www.tf2outpost.com/trade/26869131

Neither the seller's backpack or the buyer's backpack were updated when the sale was made.

Can't use this sale.

Sale #4

Sold for 40 keys pure: http://www.tf2outpost.com/trade/27040793

Backpack of seller before trade: http://backpack.tf/profiles/76561198054222437?time=1442818800

Backpack after trade: http://backpack.tf/profiles/76561198054222437?time=1442905200

Screenshot of the trade: http://imgur.com/rb7PcFL

I haven't found any evidence of sales of the other 2 Miami Nights Ground Controls selling.