I Like Mobil Oil Special pin hard to find antique

I have a really cool antique pin. It says "I Like Mobil Oil Special" The front of the pin graphics look really good, and is clean. The back side does have some tarnish. This has been ours for a long time, and I have never seen before. I did some research, and saw one about 6 months ago sell for over $50. I know it has to be the right buyers to bring that price, but I believe I have priced this fairly. It is marked on the back side of pin "St Louis" I believe it was made by the St Louis button company. I believe it was made around the 1950s or so. This would make a nice addition to a collection.