edited: moar proof.

10 keys

http://www.tf2outpost.com/trade/16052400 -unsold at 10 keys (though offer in items of 11 keys, explained below)

http://www.tf2outpost.com/trade/15984626 -sold for 10 keys after 4 days

11 keys

http://www.tf2outpost.com/trade/16052400 -offered festive huntsman 2 days ago when it was at 11 keys, though offer retracted

http://www.tf2outpost.com/trade/15032241 -offered 11 keys pure, but eventually sold for 10. however this shows 11 is possible

13 keys

http://www.tf2outpost.com/trade/16448997 -no offers

12 keys

http://www.tf2outpost.com/trade/16394985 -unsold

14 keys

http://www.tf2outpost.com/trade/15397949 -outlier, 1 month ago. newer trades prove otherwise

No offers

http://www.tf2outpost.com/trade/16088845 -2 weeks

Conclusion

Low if not no demand for this item. Low sales + can't search via trade.tf for closed trades. Previous owners of current trades were people who sold unique uncraftable archimedes, then the current owners strangified them, hence no further proof. One sold at 10 keys, whereas one had offer of 11 keys in items, hence the range. 12 keys and above does not sell.

Rest of proof from previous suggestion is too old for me to consider and it's dumb reusing proof

thanks pyroman