To make it easier for you, best to know the specific make and model of your machine. The model number and the serial number help locate a compatible item for your property. Prices vary according to product quality. Do not be fooled by brand names though. Being expensive does not necessarily denote quality. Choose what is tried and tested by other consumers.
Once you know what part you need you can then go ahead and buy it. This need not be difficult if you have a computer and Internet connection. There are many spare parts stores online; all you need is the name and model number of the part to order it and it will usually arrive on the doorstep within a few days.