Best Buy Offers Buyer's Remorse Protection with 'Buy Back'

So I buy a $200 phone (retails at lets say $600)
4 months later i get $300 50%
7 months later i get $240 40%
12 months later i get $180 30%

and it costs $50?

So I pay $50, then 4 months later I hate my phone and want a new $600 retail phone... then I get $300 back.. Take the $50 I paid for the plan so we are talking $250.

Now I have $250 credit but the new model is $600, because they are not going to give me contract price again... correct?

So if I want the new $600 retail phone I am looking about $350 out of pocket?

I think I will stick with warranty, insurance, and ebay as last resort