As soon as you are eligible, you can find out what the price is for you. Is yours the only phone on the account? Or is it a family plan? Secondary phones on the family plan get less of a discount. The discount will also depend on what your current plan is.
For example. I have a Nationwide Premium Plan. My phone is primary. I upgraded in October to the Samsung Rogue. My upgrade discount for my premium plan was $100. The online discount for the Rogue was also $100. The phone originally cost $199 for a new two year plan. This meant that I got the phone for free.
My husband just upgraded in January. He is the secondary line on our plan. He upgraded to the Rogue and the gave it to him for the current new two year contract price of $79.99. (There was a $50 online discount, the current price at that time was $129.)
So, no one can really tell you what the phone you are interested in is going to cost YOU.