Quality costs money, and this is a case where that is very true. Reaction time, db reduction, and clarity are mostly what you are paying for, battery life is another real consideration. Cheap muffs might take longer to react to the sound and suppress it, more expensive muffs react much quicker. Hearing protection is better and the overall experience is much more pleasant using the fastest reacting muffs. Clarity of sound that is passed is a big variable, some of the cheap muffs sound as bad as a childs toy radio or worse. Good muffs sound great. Cheap muffs might only reduce noise by 15-18 db, good muffs are in the 22-28 range. Db reduction isn't linear, a 22db reduction is a LOT more reduction than 18 and vastly more reduction than 15db. Good muffs will run on one set of batteries for 100 hours or more. Cheap muffs eat batteries in as little as a few hours.
If you want electronic muffs spend the money and get some good ones, they are far and away better than the cheap ones.
I use Pro-Ears Dimension Plus Sporting Clays muffs and they are absolutely fantastic. True stereo sound, great sound quality, a 25 db reduction, very comfortable, a 7 millisecond response time, over 100 hours of use on a set of batteries, and enough amplification to hear a squirrel playing in the leaves 75 yards away on a windy day if you want to. They were not cheap, but they are worth the money.