Gibbenz

Hey guys, I've got a 97 EJ6 with a manual tranny. Whenever the car is in gear I get this strange whirring/light grinding noise coming from the tranny. When it's in neutral, very little noise, when the clutch is depressed, no noise. When it's in gear and I accelerate the whir/light grind gets slightly louder. I was told it could be a bearing. Any idea what it might be/how much the part would be? I've got access to a garage and everything I need to do the labor with a buddy of mine, so costs there won't be a problem. Any and all input would be much appreciated! Thanks guys!