I've purchased most of my Haynes and Chiltons manuals on Amazon or similar sites used. I pay typically around $2 - $5 in the used condition. If your looking for the actual Ford repair manuals, they are more expensive, but can be found on Ebay.
Also, I would look on model specific forums, like Focusfanatics or F150online for how-to's written by people on the site. I replaced the timing belt on my 01 Focus a few days ago using a thread posted on the Focus Fanatics site. Along with the Haynes manual and a video on Youtube, I was able to do it right the first time and saved myself about $300.00.