For me it's finding someone that can make them. I spoke with Chris at Ujoint Off-road today and he doesn't have the equipment yet. Raul at expedition outfitters says he's never found someone who makes them for F-150's. RCI metalworks makes them but aren't really HD enough. I have yet to contact the guys at Uhwarrie off road training center.
It is always more expensive when you have to ship them, but you can try John at http://white-knuckleoffroad.com/ He took real good care of me. You could also try checking your local Craigslist for a fabricator