http://www.tf2outpost.com/trade/18956947 - Sold for a Circling Heart Shooter's Sola Topi (1.9 * 0.9 = 1.71 rounded to 1.7) + Nuts and Bolts Cosa Nostra Cap (16.5 * 0.9 = 14.85 rounded to 15 keys, or 0.8 buds, as buds were worth 19-19.5 keys at the time) + Strange Specialized Killstreak Gold Botkiller Sniper Rifle Mk.II.

As of this writing, the cheapest of the regular Gold BK Rifle is close to $10, and the cheapest Specialized KS version is slightly below $15 (though it does have a Headshots SP attatched). My guess is that it adds 2 keys to the overall value, so it would be worth 5 to 6-ish keys (or .3 buds). http://puu.sh/9vycD/5a3c45df28.png

1.7 + 0.8 + 0.3 = 2.8 buds.