80 series:
http://www.ebay.com/itm/like/1318750...978&rmvSB=true
85 series:
http://www.ebay.com/itm/like/1318486...298&rmvSB=true
These are both Ebay, the 80 series is $165, and the 85 series is $185, and the shipping is free. There are other sites with these for sale. I just typed: Sailun S637 in the search box, and all kinds of results popped up.