The truth is, I sort of despise specialized kitchen gadgets. Devices that are really nifty only once or twice a year seem pointless and cluttering to me.
I have bought the tips and bags, but the gap between projects is so large that the bits all go missing and I never have what I need when I need it, anyway.
I long ago devised a way to make the tips and bags, and while it may seem cumbersome, the fact is it takes less time to make them up than it does to wash the sticky, greasy (often brightly colored) frosting from the store bought ones.
The beauty with these is, you were going to throw away the materials anyway, so these can go straight into the trash with no clean up required.
To get started, you need:
1 or 2 soda cans
Masking tape (duct tape will also work but it's harder to deal with)
Sturdy plastic (the bags your confectioners sugar came in work well, for instance)
2 sticks of real butter
1 bag of confectioners sugar
2 or so tablespoons of water
Cut the tops off of your soda cans and wash them well. Make sure they are also well dried.
Cut off the bottoms, and then cut them into rectangles, approximately 2 inches wide.
Start rolling from the upper right corner.
Tape your nozzle tightly.
There are many tips you can make. This is a star tip, and I used some scissors to snip a jagged edge. I then carefully turned the tips inward with the flat edge of a table knife.
Trim off the sharp point on the side so that it doesn't puncture your bag.
Even though you want your plastic to be sturdy, just know that if you're fighting to get the frosting out of the tips and you're exerting too much pressure, they are going to pop.
After filling them, I rubber banded the backs.
Freezer bags are harder to fill, and messier. But you don't typically need a rubber band and lots of people find they do quite well.