We bought our own and brought them. It was only 25 bucks at walmart for the mask and snorkle and I got some flippers at a second hand store for 5 bucks. They all worked great! And I personally agree with posters who noted that the rental stuff may not be truly sterile, and with all that Norwalk virus going around do you really want to take a chance?
It was not so hard to pack, the flippers were the biggest concern size wise and I just put them in the suitcase flat on bottom. It was worth bringing.