Resuggesting with a range per polar's request.

http://backpack.tf/item/3342075080

Sale 1) Sold for a Sunbeams Tough Stuff Muffs (700 Keys) + 10 Keys + Specialized Killstreak Shooting Star (~2 Keys)

http://backpack.tf/profiles/76561198014404374#!/compare/1478131200/1478390400

700 + 10 + 2 = 712 Keys, which I'll round to 710 Keys

Sale 2) Sold for a Bonzo Nunhood (200 Keys) + CH HWNN (192.5 Keys) + Blizzardy VVF (173 Keys) + HG Grimm Hatte (59 Keys) + 10 Keys

http://backpack.tf/profiles/76561198121830870#!/compare/1478131200/1478217600

200 + 192.5 + 173 + 59 + 10 = 634.5, which rounds to 635 Keys

Nunhood Mini

http://backpack.tf/suggestion/584433228667475fe3057da9 - Using my comment, this is 200 Keys

Viewfinder Mini

http://backpack.tf/suggestion/57d9b651c4404510ea7ab686 - Using the comments, the best range would probably be 156 - 190 Keys.