Safety is a concern on this one as you don't want to use rebar incase someone falls. How about rebar but a piece of pcv pipe (4 ft or so) over the top. Hmmm I may have think about this one for a little while.
People around here use green stakes that are about 4-5 feet tall (I think they use them for chicken wire but not sure) and they put the cornstalks around them and secure them with twine. It seems to hold up pretty well.