Where can golden boy edger blades be purchased?

The Golden Boy uses a 9 inch blade with a 3/8 inch D shaped center hole. If you can't find a nine inch blade with a D shaped hole, your options include a shorter blade (i.e. an 8 inch blade will work) or an 8 - 9 inch blade with a round hole. I have successfully used blades with round holes on my GB over the years by using a good quality lock washer between the blade and the nut. Take your old blade to any lawn mower repair shop and they should have something in stock that will work. I have even found blades at home depot.