You have two different sets of questions to ask.
First, do you like the sound of GE Tritons? GE has a good reputation and a number of good reviews, but like any speaker, they are not everyone's choice. So, decide for yourself if they are the speaker you want.
The second question is the condition and price of the ones you're considering. Speakers, in general, do not deteriorate very quickly with age or use, as long as they are not overdriven. So, check their condition carefully and see if the price is reasonable. Used equipment that isn't very old and in excellent shape should typically be at least a quarter to a third less than brand new one of the same model. Take off more with age and condition issues. While there are exceptions, both higher and lower, to this generalization, I wouldn't think of GE as one of those exceptions.
