I bought my 4 inch diameter pizza wheel at a restaurant supply store. It has stainless steel parts, ambidextrous finger guards, and a 5 inch long lacquered hardwood handle. It has dual-prong wheel forks which spread the pressure on the axle more evenly. It was only $6, but it is sharp, solid, comfortable to use, and cuts pizza very well.
It replaces a 2 inch diameter pizza wheel which was part of a kitchen utensil set. The 4 inch cutter is more than twice as good - the smaller one tended to push ingredients around rather than cut them. Its lightweight construction, resulted in the axle being loose in the center hole. The larger wheel is particularly important if you cook deep dish pizza.
The pizza wheel can also be used to cut things like Quesadillas, Naan, Chapatis, or Pita Bread. It may, or may not work on brownies or lasagna, depending on the shape of the pan.
It is easy to clean in the sink. It would probably be okay to use the dishwasher if you aren't concerned about the lacquer finish on the wood handle.
A restaurant supply store is a great place to buy a pizza wheel. They usually have a variety of sturdy cutters at low prices.