If you don't need the sim when you arrive and can wait till you get in to yerushalayim then there is a table in shefa on the 2nd floor where its very good prices. It includes unlimited calls and 20 gigs of data for 39 shekel . That's a lot cheaper then global 012.
I spoke to the guy last week and tried convincing him to have someone here in the states be able to give you a similar b4 you leave