A good place to see what the .gov has to say about all this
is at:

http://www.fcc.gov/oet/info/documents/bulletins/

oet61.pdf    <~500kb> is the relevant document.
oet63.pdf    is a more abbreviated commentary incl. 'private' use

N.B. that (as best I recall) a "transmitter" is anything that can
transmit rf, intentional or not. The short answer is you can't
sell or transfer anything, but it seems VERY unclear about
e.g. a 'hobby' data link with published design but (many) 'free'
individual builders. I'd like to here anything on that (privately).

R.Martin

R.Martin