I'm thinking about adding a GPS module to my D7000 so as to avoid wondering where I've taken certain shots (an endless problem when I look back at old film photos). Any advice as to which one to buy? The Nikon option seems ridiculously expensive compared to the competition, but reviews of the modules seem to be few and far between so I'm having a hard time figuring out which third party options work well. (I've searched the archives, and although there are a number of threads that touch on GPS, none seem to do more than mention there are several options. ) Any and all advice appreciated.