The cheapest way to go, and be portable is the Garmin Etrex, about
$120 for the unit, the bad news is the cost of connectors to go to
the radio. $30 for a plain data connector, or $60 for a cable to do
data, and allow you to use a cigarrette lighter for power, instead of
batteries. This unit will supply the basic info to the radio for
APRS, but not do much if you want to look at maps and graphics.

KC8RWD
Kurt Keilhofer