I am looking to buy a flash for my cameras. I have a nikon fm10 and nikon N75 and also a canon 20d. I've had a really cheap flash for the past few years and i'm looking to upgrade to something that has more options and control. I've looked at KEH and i'm wondering if it is a good idea to buy a used flash. It seems like they might wear out over time but i really don't know. I've been looking at the canon speedlight 430x. Any recommendations?