Which vender port to buy my phone from?

[E6Engineer]

I have finally decided on getting a Razr M from Verizon as my 1st smart phone. Where should I get it from? The Verizon store, Amazon($50 cheaper), BB, Costco? Is there an advantage to any one over the others? Also, should I purchase the Verizon Insurance($7/Month) or go with Squaretrade($125/2yrs) or someother secondary market Insurance.