If you buy things for someone else and they pay you for them you are acting as a reseller. You'd quite likely draw the ire of not only the IRS but also your local sales tax folks if you don't file all the appropriate paperwork and follow the regs on that. Even if you don't actually make money reselling the stuff you still are required by law to file the details.

Do you really want to pay nearly 5% of your gross salary for a credit card annual fee? Seems pretty ridiculous to me.