Selling without PayPal

I have bought and sold many thousands of dollars thru p/p. Up here selling used parts is not considered income cause u bought them with money that u have already been taxed on. Even the new stuff I sell the tax has been paid. It I suppose like anything else that will come to an end. Used vehicals over $3000.00 are taxed every time their sold. If that used vehical gets sold 10 times, it’s taxed ten times. Kim