Josh - thought you fell off the planet there for a second
havent seen you around here much...
El Al has been the only airline I am aware of that would book an open ended *student* ticket and you would need to contact them directly or book through a well experienced agent that is familar with El Al. The problem that always comes up is that students tend to wait till May to book for a june return flight and end up stuck with no availablity.
Other airlines such a AC would just have you pick a date and pay the regular change fee + fare difference. (Birthright flights I think get a deal where the flight can be extended upto 90 days, with a change fee but no fare difference costs).
Or book a Latitude return flight which allows for no change fees (but the base price is $$$$$).
If you find something else, I would be curious to know as well.