I found my 1200-1 on my local Craigslist about a year after I started collecting sm's. I have not seen one locally since (in two years); but I have seen one or two regionally after that. You just have to stay attentive and be willing to work on cleaning one up if you find one.
From what I understand, Singer designed 1200's to be used by tailors and seamstresses. I call it my "semi-pro" model. Mine was said to be the sm of an Oleg Cassini designer's mother who was a NYC professional seamstress in the '50's. The lady's mother would sew her daughter's designs that were then shown to Mr. Cassini for review and approval. Mine was definitely used heavily as I had to replace the upper thread tensioner discs because of grooves worn in them from so much thread passing between them. I paid $60 for it and its well-worn original table.
The machine's electric motor controller is actuated by a treadle-like cast iron foot plate. The padded leather knee controller activates a combinaton of steel arm linkages which are not present on a standard 201 that are connected to the internal presser foot mechanism to raise it when the knee controller is pressed.
John Thomas in NC