Packmates aren't really that expensive. And they are WELL WORTH IT! We went to China last year to adopt our youngest daughter. We knew we would be shopping like crazy, but stuill needed to bring enought clothes with us for 3 different climates.
I ended up packing everything in the suitcases and then used the packmates only for dirty clothes. That way we had atleast 1/2 of each suitcase for purchases since the original full size clothes had been squished down to nothing!
I plan to do the same thing on our cruise! I also can sort dirty clothes by color and they they are already to be tossed in the washer when we get home!
I don't agree that ziplocks are the same. They are way to small and they are not as tough as packmates! You can find deals online all the time!