Upload/download from Garmin GPS

Has anyone managed to write code to waypoints/tracks to/from a Garmin GPS using the USB binary protocol (I do not want the serial NMEA protocol).

I found a VC++ SDK on Garmin's web site but I do not know VC++ enough to make anything out of it.

I did find a lot of links to a SDK called GPS.NET, but unfortunatly I do not thrust them. They advertise the SDK at 29$ or 39$ everywhere but when you finally get to their web site, the price suddently jumps to over 300$ for the SDK ...