It's really easy to make your own piping bag. There's no need to buy one especially if you need it as a one off. I made this to pipe icing when I was unable to get hold of a fine tube of white writing icing.
Time: 5 minutes
Materials Greaseproof paper
Cut out a triangle of greaseproof paper. You'll find it's easier to make if the triangle isn't too small.
Grab two ends of the triangle and give a twist to create a cone with a point.
Use a little tape to secure the paper in it's cone shape.
Snip the end of the cone, I wanted to pipe a fine design so took off a very small amount. A larger cut further up will make a larger piping.
Fill the bag with icing from the large opened of the piping bag and away you go.
It's child's play with my 6 year old quickly picking it up to decorate gingerbread men.