If she doesn’t want to buy chick starter it doesn’t sound like she will want to by any food as they grow and start laying. You might think about finding a them a new home if you can’t feed them properly.
Just for future reference. If you don't know if your chicks were vaccinated or not, then don't feed them the medicated feed. If they were vaccinated, the medicated feed will make the vaccinations ineffective... they cancel each other out. So at this point, continue on non-medicated feed. I'd go ahead and start feeding them Purina FlockRaiser, too, as they are old enough. FlockRaiser can be fed from day-old chicks just fine. I feed my entire flock, chicks all the way to my goslings, upwards age-wise... one feed that feeds everyone just fine, so I don't have to have multiple bags of feed for different birds and ages.