My lock button is jammed on my iPod Touch 4th gen...

I have had this device for a while and today the lock button has jammed and does not function. I do not have Apple Care and the warrenty ended a long time ago. The device has a small dent on the top right corner (the same place as the lock button) because I dropped it over a year ago. I am fairly sure that the dent had nothing to do with the button failing because the camera has always been fine. If I were to take it to the Apple Store how much would it cost to have it fixed? Would I just have to buy a new iPod because it is out of warranty and they assume it was the drop that killed the button?