Soon after, he received a letter from a man in Sudan offering him many more slaves. You don't know if after several days these groups of people get reabducted. Interestingly, the price for slaves is dropping, which argues that the supply is exceeding even the increased demand. This is an inference drawn from principles first taught by Adam Smith. Price Theory is relatively new though, originating only in 1776, so it's probably unfair to expect schoolteachers to have heard of it.
Redemption is counterproductive.
If somebody cares, the local people should be empowered to defend themselves against slave raiders. I would be stunned and delighted to see school children raising money not to buy slaves, not to buy tractors, but to buy guns. Barb Vogel, fifth-grade teacher at Highline Community School in Aurora, Colorado, got it into her head to do something about slavery. She roped her students into doing it with her. If the children had suggested playing hooky or playing hockey or playing with a hookah, Ms. Vogel just might have shown better judgment.