Well,
You could get something like this.
A TC display like Betso's TCD1, hooked up to your lockit box, could be a money saving option. Supports all standard DF/NDF FPS, and shows User Bits too.
The downsides would be having to attach a clapper of some kind, and the numbers wont "stop" at the clap. It has an internal rechargeable battery, or DC power. The screen turns off for power saving after inactivity.