Picking and weighing individual items yourself doesn’t take much more time. The extra cost is for convenience. So, the next time you’re shopping, remember that pre-packaged items often carry a higher price tag than their individually sold equivalents.
Plant your scallions in potting soil and water them daily. They start to root quickly. You can grow a lot of your own vegetables from produce you buy from the store. Research the easiest produce to grow at home.