My ball fringe came from Hobby Lobby, and cost about $7 per yard. You can find something similar here.
The trick to making ready-made curtain panels look custom is training them. Training is the simple process of tying the panels into soft pleats and leaving them tied for about a week. When you untie them, you are left with professional looking pleats that will stay in place and even return after being opened and closed.
Curtains in training.
Adding trim to curtains is just one way of personalizing a store bought item. I think everyone has their own way of taking things from off-the-rack to over-the-top. What's yours?