It is illegal to carry them back or ship them home, etc. It's all illegal unless you have a license to import them and schedule all of the inspections you need, and perform all of the customs paperwork and routines. It's a pain in the ass, and it's definitely not worth it. There are not enough customers willing to pay enough. You might make some money, but you will work very hard for that money, you would be better off just getting a part time job, it would pay more and be less work.