I would not pay 600$+tax for an iphone and then... pay 135USD to unlock it... Ill wait for te iphne price to lower..
Hunt for the instructions on how to do that and you'll understand the price!!!! Yes, you can do it for free, if you're a tech pro and can do it with out messing up!!! It would take you about an hour and half to do it! That alone makes it worth da money!!