If you are looking for used stick with quality. Assuming you do not want to spend big big bucks I can recommend Chang Lightspeed or Vansevers. They are both built well to last. I have a Monster that does a good job with cleaning up my TV picture and video. Colors sharper. Not good enough for good audio.
AC Conditioners?
Interested in a used AC Conditioner but don't know much about them. Can anyone tell me if they lose functionality as they get older? Do they where out? Do they not filter as well after protecting from some kind of surge? What are the considerations and what questions should you ask? Appreciate any info anyone can provide....