Where can I find the brake petal stopper that turns off the brake lights?

This is a plastic plug/stopper that attaches to the brake petal, it pushes the break light sensor in, which turns off the brake lights. The brake light switch is a little box with a button(like the light sensor in your fridge, or sometimes found around car doors to detect if they are open), the idea is it give power to the brake lights until the button is pushed in(not pressed in, the brake petal keeps the button pushed in), when released (push the brake petal) it will turn the lights on. There is a gap between the brake petal and this button, so a small round plastic piece snaps through a hole on the upper brake petal to fill this gap(and push the button, aka turn the brake lights off). I've called auto parts stores, but the people I talk to seem oblivious, I know it's not as easy as a battery change, but I came across these things a couple of times, and my job is not related to cars at all. I would like to know if they actually do carry these parts, as they seem universal and fairly common.