In the 1950s, there was a huge trend for plastic ukuleles. Leading the way was the Maccaferri Islander.
Maccaferri had previously been famous for making jazz guitars - particularly those played by Django Reinhardt. When plastics first started to be used to make instruments, Maccaferri jumped on the idea. Plastic meant that ukes could be made quickly and cheaply and sold by the armload.
Unfortunately, Maccaferri ukuleles aren't exactly cheap anymore. The value of them seems to be rising - particularly if they still have the original packaging.