I got my 12-string like this (but not nearly so good of a deal). I stopped at a garage sale, and saw what looked like a photo of a Martin 12-string in the back, along with some other photos. I asked what the pictures were, and the guy running the sale said they were items from another sale that he hadn't brought that day. I asked about the guitar, and he said he didn't know anything about it, but it was priced at $75. I told him I was interested, and he brought the guitar for me the next day. It turned out to be a '60s Takamine (lawsuit guitar), but for $75 I couldn't have been happier.

That guitar is still has the sweetest action and is the richest sounding guitar I own, including my "real" Martin.