Proteins are composed of 20 ammino acids, and BCAAs are only 3 of those 20. So, short answer, you cannot replace your protein intake with BCAAs. 4 oz of chicken is 25g of protein, while you would have to eat 4 oz of BCAAs to consume the same amount in terms of calories, so you haven't "saved" anything, especially not money.
Do you drink protein shakes? This is why they were invented.