Resuggesting, past suggestion missed a pro that was listed for 9 that was up for a week. Largely copy-pasting my comment from that suggestion.

10 keys:

https://backpack.tf/profiles/76561198844647910#!/compare/1533254400/1533340800

Looks pretty clear, the keys and Eyelander are only items of any significant value

10 keys:

https://backpack.tf/profiles/76561198026194410#!/compare/1534809600/1534896000

Sale from previous suggestion, see suggestion for screenshot: https://backpack.tf/suggestion/5b7d090fcf6c750a1f34621f

9 keys:

Compare link is a big pain: https://backpack.tf/profiles/76561198006544512#!/compare/1535500800/1535587200

(Other side is even less useful https://backpack.tf/profiles/76561198289553400#!/compare/1535500800/1535587200 )

I just asked the seller, who confirmed it went for 9 pure, I assume the buyer probably got keys from Marketplace that day or something. Sale was on 8/29-30, at least six days after the prior suggestion, and the listing at 9 keys was reasonably matured.

Chat screenshot: https://i.imgur.com/fZNjxV0.jpg

No current sellers on classifieds or outpost (rest in peace), sales at 9 and 10 keys. At least one other seller at 9 keys was mentioned in the past suggestion.