The last couple of times that I have done suspension rebuilds, I have used Rockauto for parts. They generally have a good selection of Motorcraft parts. Some people also buy from Tasca Ford.
The online parts sources are convenient, but you need to make sure that you are ordering all of the correct parts. If you have to return something, it can quickly become inconvenient and less cost effective than purchasing everything locally.
When you are looking at parts, I recommend that you consider purchasing new front control arm assemblies. They come with the ball joints and bushings pre-installed, which saves a considerable amount of time and frustration.