I have no idea what the final cost would be for it, but I think it’d be really helpful to have a smps for a breadboard. The power supply I use is a 24V laptop power supply, and about 50 watts. So if I had a perfect smps, I could get about ten amps, but with a linear regulator about 2 amps(and probably with a fan mounted to the heatsink of the regulator). But with the hall effect sensor, the board could also have an LCD showing the voltage and amperage along with perhaps a shunt transistor for underloading conditions normal for hobbyists. It’d be best to allow variable voltages with a trimmer, to help simulate a wall wart or battery when using another regulator for the circuit and to help guage the actual amperage used including another regulator.