Hello, I too have a Sigma Anniversary Model Guitar. I bought it in 1980 and was looking for its value today as my neice is looking for a guitar.   I bought it to take lessons and asked the salesman for a guitar that I would never be disappointed with.   

After reading this website - it was a good choice. I had no idea only 100 were ever made.   I am not sure I want to part with it now. It is in perfect condition. Glad to have found this website.