This is investment. If your kids are socially rejected at school and can't get on the internet, are they going to be better off in the long term or worse off?
If you are poor, looking poor is not going to help you up, it's going to drive you farther into poverty. It's the same impulse that makes lower-middle class parents go into debt to put braces on their kids' perfectly functional teeth (in the US.) Your kids are going to have to impress fellow students, charm their teachers, get into colleges, and interview for jobs. A bunch of people who don't see class are going to see your crooked teeth.