If I went to the sprint store how much would I have to pay them?

[bill n]

I want to know if I went to the sprint store how much I would have to pay for a lg rumor 2 so like if i wanted to pay in cash would I have to pay like 80$ because the price if you look online says 29.99 with 50$ mail in rebate and like 170$ instant saving do I pay only the 29.99$ and mail in rebate