Penguin was founded in 1960, and ceased production of the pen-guns sometime in the 70's. The first model was black and white, made for a JA project, and the kids involved thought the coloration made it look like a penguin - thus the company name was born.
Is this what you have?
I have looked around a bit, and find prices all over the map for these, from $7 to $175, depending.
Now, I am NO EXPERT on these; the above is just what I turned up in a web search.