It all depends on the customer and brand of mower. If they are in a rush to get there mower back I just go to the local dealer and charge the extra cost to them. I have had in the pass very good luck with Jack's. Now John Deere is a story in itself finding parts. If I am shopping for price I will look on E-bay and the web. Parts like lubrications, hardware, plugs, and filters I buy from the local auto parts store. Them once a year I will go to a trade show and buy a larger amount of the parts that I use all the time like gas filers, electrical fittings, wire, hose, etc. Common size bearing and seal I buy by part number and will order a large amount of them from E-Bay. Being a small repair shop parts buying parts is one of the biggest jobs I have