Why is sprint jphone 5 cheaper than other iphones 5?

I'm interested in purchasing a iphone 5 to unlock and take to colombia. Why is the sprint 5 cheapr that others, 2nd can i unlock all iphone 5?

Because sprint sucks, you get no service anywhere and they try to lure people in

It's cheaper because Sprint is giving you a bigger discount.

Buying it from Sprint will mean it's locked to Sprint. A new unlocked iPhone 5 is around $600.

Its the slowest of all iphone and it can't be unlocked.