Needed a mini for this and the current suggestion was a bit confusing so decided to look into the sales and found another one.

Sale 1

Sold for 5 buds (5.5) and 20 keys = 48 keys

http://www.tf2outpost.com/trade/25710511

Buyer before: http://backpack.tf/profiles/76561198001403207?time=1429254000 (April 17th)

Buyer after: http://backpack.tf/profiles/76561198001403207?time=1429426800 (April 19th)

Sale 2 - 100% credit to Ƹ >☼.Lockworks☼< Ʒ

Sold for mallard spook specs (50-60) and pro ks big kill (10) = (55 + 10) * 0.9 = 59 keys

Seller before: http://backpack.tf/profiles/76561198115974835?time=1428822000 (April 12th)

Seller after: http://backpack.tf/profiles/76561198115974835?time=1428908400 (April 13th)

Sale 3 - 100% credit to Ƹ >☼.Lockworks☼< Ʒ

Sold for 30 keys pure - quicksell

http://www.tf2outpost.com/trade/25378112

Sale 4

Sold for GE billycock - this is the sale I needed the mini for, so not using it

Buyer before: http://backpack.tf/profiles/76561198074704764?time=1426230000 (March 13th)

Buyer after: http://backpack.tf/profiles/76561198074704764?time=1426402800 (March 15th)

Mini for pro ks big kill:

Average buyer pays ~$25

Average seller receives ~$21.25

Scm key price ~$2.35

25/2.35 = 11 keys

21.25/2.35 = 9 keys

Range = 9-11 keys

Feedback welcome