i find almost all lash curlers to be about the same. what you are really paying for is the name, and because of that you think the name brand ones work better. what you really wanna look at is the padding on it. you want to replace the pad when it becomes too soft. and after a few years, replace the curler itself.
for years i was using the sonia kashuk curler, and it worked great. i recently switched to the mac one, and it curls the exact same. the only differences are that it is slightly shorter from corner to corner, so my outer lashes don't get curled, and i don't think the sk ones come with a replacement pad like mac's does. no biggie.