Puppy won’t eat expensive food (Australia)

Hi. I have a 13 week medium breed X puppy. She was eating Hills Science diet but I ordered 2 1kg bags of blackhawlk dry puppy food (Because it was cheaper) and the first morning I gave it to her she only ate half and the 2nd day we had to put some egg in it to get her to eat it.. it was $34 just for 2kgs and the Hills is $40+ $10 delivery at Petbarn for a 2kg bag. Is there any way to entice her to eat it, because I don't want to be feeding her egg every day, and I'm on a disability pension, so I can't afford to play musical dog food. tia