Some people just don't know, perhaps he's confused with the SQ-W? The the SQ-M was the basic becoder, no logic at all! It looks the same as the SQ-L Front to back logic decoder, which should only bring around $50.
If you only want it for the nostalgia aspect, $50 is way too much. Even the SQ-L, with its partial logic, isn't worth it. The SQ-W is the only Lafayette decoder worth seeking out, but again, just for the nostalgia. Its "Composer" setting is basic RM; no logic enhancement there.