This is my first price suggestion on an unusual and yes, I know that I have one, but the price is pretty old.

Here are some offers I found:

http://www.tf2outpost.com/trade/3407705

offers:

20 keys+a gold botkiller sniper rifle with strange part scouts killed,descr tag,name tag, but seller hast to add sweets;

Bubbling Handyman's Handle (15-19 keys);

18 keys;

white Purple Confetti Backbiter's Billycock (14-18 keys) + g. AWPer (1 key)

http://www.tf2outpost.com/trade/8042469

B/O: 1.5 buds

Offers:

Bubbling Dr's Dapper Topper (22-25 keys);

Orbiting Planets Hetman's Headpiece (13-17 keys) + Painted Villians Veil + 1 Craft hat;

Bubbling Handyman's Handle (15-19 keys);

Circling TF Logo Madame Dixie (16-19 keys);

14 keys and a festive rocket launcher (3 keys);

18 keys;

white Purple Confetti Backbiter's Billycock (14-18 keys) + g. AWPer (1 key);

http://www.tf2outpost.com/trade/9635328

B/O:

23 keys

C/O:

19 keys;

N&B Prince Tavish Crown (13-17 keys) + sweet;

purple confetti white billycock (14-18 keys) + genuine awper hand (1 key);

http://www.tf2outpost.com/trade/10509227

C/O:

B.M.O.C. (11-12 keys) + 5 keys + sweets (offer retracted)

http://www.tf2outpost.com/trade/10765700

C/O:

Smoking Prancer's Pride (15 - 20 keys) + sweets

http://www.tf2outpost.com/trade/10533391

offers:

Steaming Tippler's Tricorne (16-18 keys)

Last but not least, my trade: http://www.tf2outpost.com/trade/10698516

C/O:

Orbiting Fire Shooter's Sola Topi (16-20 keys)

I was not able to find any sold Brain Buckets, so that is all I can provide.