○ It depends on whether your joist is warped or not. If the joist is warped, it is expensive. It depends on many of them you need to replace. If you just need to screw it down, around 30 cents per sq ft.
● You need to level the joist,some old houses even the joist can be warped since it is solid wood. If you need to replace your subfloor you need to glue and screwed down. If you don't replace your subfloor, you need screwed it down but you might still have some noises.