They do not charge you but rather pay you to do the jobs. You are likely to have to put out some cash to be reimbursed. Jobs you perform for them in July will be paid the last business day of August by direct deposit to your bank account.
I've been doing jobs for SI for a couple of years now and they direct deposit and pay on time. A good company to work for but sign up for the subscription shops. They have a ton of phone shops in my area.