If 'm already paying 149.99 to replace my water damaged Iphone 4 can pay Iphone 4s replacement price and get instead If No explain why please . Thank you

I have a water damaged Iphone 4 I have had for only 8 months. Today I went to the apple store to see how much a replacement was and the girl told me 149.99 for my iphone. What I was wondering is can i pay the replacment cost of an Iphone 4s and get that instead . I dont see the problem since my phone is broken anyways . But I would like to hearf if any one has tried the same thing.

Thanks