There are a great number of places you can check. Here in Reno, in addition to the haul always my shop takes in, I am friends with other small, independent dealers/servicers who know what I want. I occasionally check in with them so they remember me. Also, the thrift stores are not to be overlooked! I have made many great finds at the Salvation Army clearance wherehouse where the 'as is' stuff shows up. There are multiple organizations who haul away donations like old appliances. Some are nationally known but many are small, local charities. Networking is key here! You may or should tell them that you'll be willing to pay a small donation for good machines that they would not normally sell or fix but might get a small amount selling them as scrap.
Most of the big box stores like Lowes, HD or Sears most likely are write offs as they either have a deal in place with some local co to haul away their trade ins or just outright scrap them for money or for store policy but sometimes you might get lucky. Then there's always C/L...
Good luck and good hunting!
RCD