To resurrect this thread after two years, the SAM-III magnetometer kits are now available from Whit Reeve in the US (Alaska). The kits have progressed hugely in the past year or so, and Whit has done an excellent job turning the thing into a thoroughly professional product. See his website at
http://www.reeve.com/SAMDescription.htm
I have just purchased one of the kits (not cheap - over $400 landed in Oz) and it is very well done, especially the manuals. It's not a kit for someone unused to soldering printed circuit boards. I'm busy building mine at the moment.
DN