3 letters are more valuable.... 4 letters are more subjective. Really depends... theres no hard and fast rule to that
I agree with the others.. it depends on the Domain name and its value..not the number of characters really..
It really depends on what those characters are. For example, random 4 characters are worth $0 all the way to something like a 4 Letter name like Porn.com which would be worth $x,xxx,xxx
yes..4 letter .COMs can range from nothing to a couple hundred dollars..and there must be quite a lot of random ones still available..