I'd go with Maytags, they tend to turn up the most often, so you will probably find a match the easiest. Check craigslists in your surrounding states and maybe western North Carolina and eastern Tennesee. I look in the appliance and antique sections. Search for "antique washer", "antique washing"", vintage washer, vintage washing, green washer, green washing, etc. Also check the shoppers square.
Do this about once a week, be devoted, and aggressive (jump while the irons hot and don't be afraid to travel) and I bet by the new year at the latest you'll be washing in avacado goodness. There are still a lot left.
I remember a year or so ago, I found a matched set of avocado Maytags between two North Carolina counties and put them on here. My sets that I've gotten actually came from different states to find a matched pair. My Maytags are from Ohio and Maryland, the Kenmores are from North Carolina and Michigan, and the Westinghouse are from Maryland and West Virginia. Don't be discouraged, it will come.