Never tried electrical tape but that leaves you with having to fill a spool with braid. The purposes of backing are two-fold: one gives you the grip on your spool that your braid needs and secondly it requires less braid to be put on the spool thus saving you money.
Then, when you would otherwise replace the braided line after good use you can actually just unspool the braid and re-spool in reverse order. Ta-da! New braided line.
If you can't find em wind em.