In an emergency, electrical tape might work if you put down maybe three, four layers of it, as the material is too soft to resist splitting or cutting by possible sharp edges from the holes at the spoke nipples, especially if you have a tire/tube that requires high pressures.
Bottom line is, rim tape is not a good area to skimp. Just buy the right stuff and you will be more confident that you don't get a blow-out during a ride because you used the wrong tape on your wheels.....you might be saving yourself from major injury or worse....

Chombi