This particular Featherweight is definitely in the category of Rare. Economists know there is a distinctive difference between Rare and Scarce. One is limited quantities and the other is limited available resources with which to obtain ... so in all honesty, this machine falls into both categories!
At the 1940 World's Fair held in San Francisco very few Singer Featherweight machines were promotionally badged with the Golden Gate emblem. As you'll see at first glance it looks very, very similar to the Centennial badge frequently seen but has the engraved title "Golden Gate Exposition San Francisco 1940".
A customer sent this machine to me on consignment a couple of weeks ago. I just finished taking photographs for an interested client but thought I would share the love by showing this unique Featherweight 221 for everyone to see.