Hello,
we run the biggest (German Language) Information site on Geotagging.
We sell high quality 3rd party geotaggers for Nikon DSLR (there are no 3rd Party geotaggers for other brands, yet)
https://www.gps-camera.eu/shop/nikon-geotagging/nikon-spiegelreflex-dslr-gps-geotagging.html
The other categories of the shop list all geotagging cameras (GPS-on-Board, GPS-Interface) but point to external offers, for now.
Comments welcome.
Cheers
Seb