Hi Tom,
Are you talking about the breadboard or the “Parallax Joystick Interface Boards”?
The breadboard can be purchased from a number of places including Parallax: 6 3/4" x 2 9/16" Breadboard - Parallax
The “Parallax Joystick Interface Boards” come with the joysticks and are intended to plug into the breadboard: Gimbal Joystick - Parallax
Please let me know if you have any other questions.
Best,
Rusty