Where can I find Mth S Scale track for sale?
Amazon. If not pictured, type in a request for it in the box where they say they want to enhance service and they will find a source for you. This process worked for me.
Port Lines, Pikesville Models, Trainworld, Ebay
Doug Peck at Portline Hobbies: portliness.com
I have some extra S-HELPER track which works with the MTH. What do you need?