Help Repairing a Receiver?

Hey everyone, I also posed this on Android Central, so if you read/post there as well, sorry for you seeing it twice. Posting here as well to draw in more feedback from you brilliant folks!

Anyway, I have an AT&T Galaxy S4. The water indicator under the battery is pink, so I can't trade my phone in for a warranty claim, and I don't have insurance. So, I'm left with repair.

Ok, here's my problem:

I can't hear anything through the receiver (speaker on the front) while making a call. Speakerphone works fine, as does plugging in the S4 headphones or using bluetooth. I used the *#0*# to bring up the service menu. When I press the receiver button, nothing happens, but the speaker button plays audio as expected. This to me confirms it is a hardware issue, unless someone has some other suggestion.

So, my question is... it this likely something repairable, and if so how much would it cost to have someone fix it? Could I potentially buy the part and do the repair? I've never done cellphone repair before. I'm wary of trying.

Anyway, any advice would be appreciated!