The SIM-free version of the water and dust proof Samsung Galaxy S4 Active (http://www.gsmarena.com/samsung_i9295_galaxy_s4_active-5446.php) has just gone on sale in the United Kingdom. The tough smartphone has been available through a few carriers for a few weeks now, but it's only now that you can get it without signing a contract.
The lowest price for the SIM-free and unlocked Galaxy S4 Active we were able to find is