I've always kept store-bought ties like the ones pictured below on hand, but always felt like I had to ration them out. The cost can really add up when you only get a dozen or so in a pack that cost 2 or 3 bucks. The cable ties on the far left are essential for other garden tasks, but can cut into the tender skin of your tomato vines, leaving them injured and susceptible to disease.
I personally don't wear panty hose, but bought some just for this purpose. This pair cost me only a dollar (at the handy dollar store within walking distance from me) and will give me dozens of ties.
Just take the panty hose and cut a length from it. It will stretch out and tie easily around your vines. The material is soft and gentle and you won't have to worry about the homemade ties cutting into the vine and hurting your plant.
Now go search your drawer for some old hose you know you are never going to wear again, and tie up some tomatoes!