Like others have said Borax is optional, and I would guess the majority of us have NEVER used it. That being said depending on your particular water conditions you may find adding Borax improves your pool experience, but you can always cross that bridge if and when you come to it.
BBB is really about understanding pool chemistry and only adding the things needed to maintain your pool, this often means not using various magic in a bottle quick fixes made up of unknown chemicals, etc. At the core there is nothing in BBB that means you can't purchase your baking soda from the pool store at 200% markup, the same goes for Liquid Chlorine / Bleach, etc. Just many of us think it is foolish to overpay for things. Hey I admit I sometimes do it anyway, I just bought a 10 pound tub of TA up (Sodium Bicarbonate) in other words baking soda at the local pool store last week, sure I could have bought it for half the price at Wal-Mart, but I was in the pool store anyway needing a replacement skimmer basket and did not want to make another stop. The point is here I knowingly bought the chemical, not some magic stuff that raises TA.
Ike