This is not a BOGO deal but it is how I got my Sprint Galaxy S4 for only $139.99.
Samsung Galaxy S4, Black (Sprint) Amazon link
It appears to be a random thing but occasionally when I would click on the "Family Plan" and then "Upgrade" it would show up as $139.99 instead of the $199.99.
Great thing about Amazon is that 2 day shipping is free for phones.
So for my upgrade to my family plan I spent only $139.99.
This is still cheaper than going to the Sprint store and getting charged $250 and praying that the $50 rebate actually works in order to get the phone at $199 like they advertise.
All it takes is some minor error on the rebate card and they can deny the rebate.
For example, using an abbreviation in an address can potentially invalidate a rebate.
Plus the close to 12 weeks you have to wait to find out that the rebate has been rejected or accepted.
Stick with BestBuy who absorbs the rebate for you and offers you the phone at $199.