How much to fix a piston pin or wrist pin issue for my LS1 (modified, headers etc...) for my T/A (00 model)?

I took it to a mechanic and his best asumption without tearing into the motor was a pistion pin issue. Although he did say that may rocker arms were ok I really dont think he wanted to get involved with my motor cause of the time and he knew (since it wasnt a speed shop) that he probably wouldnt be able to fix it anyways. I am hearing a tapping noise from the engine and it seems deep down cause I cant really tell what side its coming from. I know its nothing simple like carbon buildup and fan belt or anything like that. I was told it could be a valve lifter or rocker arm but I 'm just trying to be ready for the worst case senerio here. The noise doesnt go away but it did lighten up a little bit whenever I added oil. But it is loud enough to hear while driving and it goes along with the RPM. But the lower the RPMS the louder it is. And suggestions or help?!??