In my club in Argentina (www.cpz.com.ar) the instructors are
volunteers and the club compensates some of their time and trouble
with a free tow or its equivalent in monthly dues for every eight
instruction flights. There are no special rates for instructors. A few
other clubs here have a similar system but in most there is no
compensation. The club pays for insurance and in some cases helps with
the instructor rating or renewal fees.

Juan Carlos