I'd like to buy some of those elastic bands to take with me while travelling. They fit in any backpack or suitcase and make it possible to do some resistance training while on the road.

The thing is, I'm confused by the different offers. They sell from $2 to $25. What to do? Go for the cheap ones or buy the more expensive brands? Any recommendations?

I'd recommend those bladders on bars that you just fill with water to make light portable dumbbells.