We posted two picture guides on how to replace your PS4 hard drive and how do the post-installation for the firmware update. I wanted to share a video that gamespot released for those who prefer that method.
If the video goes too fast then check out the guides below.
Hard Drive Recommendations that will work with your new PS4
UK Hard Drive Recommendations
In the UK the prices are VERY different but the cost of delivering it from amazon in the US can reach up to $100 as well.