You don't need to buy anything. The tradition is that it can be anything from a useful item to a piece of junk. At one company I worked for, the item that went around every year was a plaster cornucopia. Each year it got spray painted a different color. At another place was a lamp repair receptacle complete with bulb.
One of the things at our family Christmas that keeps popping up is an old chamber pot with the bottom rusted out. Couple of years ago, I got a coon skin hat at our club party. It's all in fun.
