The 221 is a piston filler from the simpler Classic range. According to the standard reference “Collectible Stars” it was made from 1971 to 1979. In its certificates of authenticity Montblanc lists it as the M 221 FP Classic. It is a standard pen of those years, built in large numbers and correspondingly common on the collectors' market.
Two things follow from that. A strikingly low price is no indication of a fake with this model, merely a reflection of how widespread it is. And there is no collector value in prospect that would justify an elaborate restoration. As a pen to write with, on the other hand, the 221 is rewarding: the piston mechanism of this range is simply built, spare parts are easy to come by, and an overhaul with a new seal is routine work for a specialist workshop.