Here's another option for a cheap Bluetooth pedal. Easy to make, no need to have any knowledge of electronics, and it works great 
I'm working in vocational training for disabled teenagers in Egypt. Besides other items we're making Cajons. So I made a Bluetooth pedal in the same style as the Cajons, see attached pictures. I kept the mouse as it was, I only removed the scroll wheel. There's an opening in the bottom which enables me to switch the mouse on and to change the battery.
I'm working in vocational training for disabled teenagers in Egypt. Besides other items we're making Cajons. So I made a Bluetooth pedal in the same style as the Cajons, see attached pictures. I kept the mouse as it was, I only removed the scroll wheel. There's an opening in the bottom which enables me to switch the mouse on and to change the battery.