I was thinking that if Sarah was working in the shop every day since July, she probably had to defer her course. They would have needed at least one trained and trusted person in the shop, and somebody here reported that other staff had recently left--to Sarah's anger if I recall rightly--when Karen disappeared. So perhaps they couldn't find suitable staff or couldn't afford to pay them properly. Without Sarah, the shop couldn't run, and I imagine they couldn't just close it down without losing the value of the business and perhaps still having rent commitments on the space for a period. The best thing in that situation would be to try to sell it, probably an especially slow process with rumours about of the family's financial difficulties.
So I can understand Sarah feeling stuck and hopeless and her friends wanting to raise money to send her back to school.