Going with a range suggested by a moderator

https://backpack.tf/suggestion/5d39cb0fd38172204a126ed3

https://marketplace.tf/items/tf2/30658;5;u99;strange

https://backpack.tf/item/4226181683

206 keys

Thank you to the user involved for the following screenshots:

http://imgbox.com/hLzAcWu6

http://imgbox.com/Ra8vbiOe

http://imgbox.com/cPOiFLDq

https://backpack.tf/item/4269220997

$400 / 1.75 paypal = 229 keys

and 9 keys for a total of 238

//

Current sellers:

https://gyazo.com/b409be44162bff989cc4ade40019c382

300 keys for 12 days https://backpack.tf/item/4269220997

300 keys for 1 month https://backpack.tf/item/4226181683

https://marketplace.tf/items/tf2/30658;5;u99;strange

https://backpack.tf/item/4814103434

$499.00 (~275 keys)

Exactly how long it has been up is unknown, but at least since June 28, 2019

https://webcache.googleusercontent.com/search?q=cache:4yvJLyfOH3kJ:https://marketplace.tf/items/tf2/30658%3B5%3Bu99%3Bstrange+&cd=7&hl=en&ct=clnk&gl=us

The second seller kinda gets cut off because I don't know how the zooming thing works on this, but I had to zoom out pretty far to show that it was still there

https://gyazo.com/5e7f00ca6af180fb0fe086991998110b