by "part" you mean the actual bearing?
~$60.00..
Hell, if you are willing to spend the $150.00 get an entirely new knuckle (already has a bearing pressed in and you can change it yourself, now (without needing a press).
Call Tousley ford and speak to Steve..
1-800-328-9552
Mention that you heard about his "svt" plan, and he will give you anywhere from 40-61% off of your parts. (new knuckle ends up being 166.00 shipped to your door., instead of 225.00 PLUS shipping.
Ray