Forum Moderators: buckworks
If you sell t-shirts and make money from them, the default is that you have to claim it on schedule C of your form 1040.
You don't need a federal Tax ID as a Sole Proprietorship. You can get business banking accounts, paypal accounts, and credit card merchant accounts just fine with your social security number as a sole proprietorship.
If you choose to organize your busines in some other manner (e.g. corporation, LLC, partnership), then you'll need to go through some of the rigamarole of paperwork.
I'm not sure about your state, but in mine, I don't need a "business license," just a sales tax certificate. Each quarter, I have to report to the state what my total and taxable receipts were, and write them a check for the taxable receipts.
Its all actually very, very simple. It only gets time consuming if you do a lot of transactions.
PayPal comes with limited shopping cart capabilities. You may also want to check out Mal's E-commerce which is a very nice entry level hosted (and cheap/free) shopping cart service.