We tried carpet strips...they were great for stopping erosion at the swale edge...not so great on flat ground for many of the reasons stated above.
When we moved to this house, there was a roll of "tar paper" Builder's felt left on a shelf in the back shed. It worked very well for establishing walkways and borders. It may work well for you as it is relatively inexpensive, easy to cut with (old ) scissors, lasts a long time, (we used a layer of cardboard under a double layer of the felt and topped it with gravel for the walkways) and is fairly easy to work with.
http://en.wikipedia.org/wiki/T...
