I think the number of sellers should be sufficient to drop this beast, but I might be wrong.

Gonna do it anyways.

Suggesting at 26 keys.

Sales at 26 keys:

http://www.tf2outpost.com/trade/27962490 (Sold non-killstreak wrench, 11 hours)

Sellers at 26 keys

http://www.tf2outpost.com/trade/27956257 (2 days)

http://www.tf2outpost.com/trade/27914727 (1 week, with parts)

Sellers at 27 keys

http://www.tf2outpost.com/trade/27952965 (3 days, spec ks)

http://www.tf2outpost.com/trade/27941411 (6 days)

http://www.tf2outpost.com/trade/27935242 (1 week)

http://www.tf2outpost.com/trade/27920143 (1 week, on SCM)

http://www.tf2outpost.com/trade/27918971 (1 week)

Classifieds

Buyers:

http://i.imgur.com/n1dIS9z.png

Sellers:

http://i.imgur.com/xqumr73.png (Page 1)

http://i.imgur.com/onueM43.png (Page 2)

http://i.imgur.com/Y8BPvAL.png (Page 3)

Conclusion:

There is a full page of sellers (spec ks and non-ks) at 27 keys. 25 keys sellers likely to be outliers. Choosing 26 keys, despite 26.05 keys buyer and quicksale at 26 keys. Feedback or more evidence/counter-evidence will be appreciated.