Upvote. No offers for 16 keys. Lowest is 17

Downvoted. Try selling one of these for 17. I've sold 3 or 4. It's possible, but getting more than 17 isn't. It's a well liked item, but really low supply and not an outrageous demand.

You posted 2 trades that had the same over 17 offer. He bought at a premium.

I bought one for 16 keys but it was a few months ago.

It looks like most sellers just go for the TF2 Spreadsheet price on this one, as the volume is way too low to have any sort of competition among sellers. There are only ~2 pages of search results on Outpost, and a lot of those are sold as well.

If I were to take a wild guess I'd imagine the price to be 16-17 keys, but until someone posts here that has bought or sold the thing, it's hard to say.