Those that want to consider the environmental impact can go "green" with a miniature hand-operated version. They are inexpensive and use very little soap and water, and no electricity. If you want the absolute king of the hill when it comes to engineering and performance, treat yourself a Miele washing machine.
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.