I have seen people trying to put it to 14, but I think that's jumping the gun a bit for now.

http://backpack.tf/stats/Unique/B.M.O.C./Tradable/Craftable: Not even a single person at 13.5 but I think we should raise the price a bit slowly just in case

http://www.tf2outpost.com/trade/21922512 16 key C/O on a pink/ Halloween spell B.M.O.C and that's on outpost!

http://www.tf2outpost.com/trade/21901539 White bill's + 8 keys ( So if pricing the bill's high that's 15 keys or if you're gonna sell it for 6 keys that's 14 keys for a pink B.M.O.C) also is a C/O

http://www.tf2outpost.com/trade/14245786: offer of a Prof. rocket launcher kit which I'd say is like 18-19 keys from what I gathered on the steam market

Also almost all of the B/O's ( i know b/o's but still) on outpost are above 14 keys I don't wanna link them all but ill put the general B.M.O.C outpost listing here:http://www.tf2outpost.com/search/219626747

BTW this is my first suggestion so please give me lots of criticism.

Sorry its taking so long to find other sales, its kind of a slow process going to people asking if they've sold and B.M.O.C's lately