I'm a coupon shopper. I'm able to purchase merchandise at local stores for 90 percent off retail utilizing coupons. In my city I'm allowed four garage sales a year. I'm planning to have one per quarter to sell the stockpile I accumulate every three months. Usually, my stockpile's worth ranges from $3,000 to $5,000. Because this is a significant source of income, do I need a business license for tax purposes or for any other reason? I want to keep the spirit of the garage sale (cash only, no receipts, no tax).