ball joints 01 mountaineer/explorer

I took my mountaineer (expensive explorer) to the alignment shop and was told that i needed new upper and lower ball joints and a rack and pinion(girlfriend hit a curb. Women!!! LOL) :confused: . I was told by the shop that it would cost $1700 to fix but I found the parts online for less than $400(go figure LOL). Anyway they told me that the upper ball joints cant be replaced by themselves you have to replace the whole control arm which I already knew. But they said the lower ones could be replaced by themselves but my haynes manual says you have to replace the whole control arm. Anyone know who is right?
It's an 01 with the 5.0 and it's AWD.

Hi there bumpinkicker04, I have a 1996 EXP 5.0 AWD and have replaced the lower ball joints when the manual had stated that the complete lower control arm had to be replaced but of course the parts store had the lower ball joints separate, but the upper are a different animal, complete arm replacement required. Could you fire me an email and let me know where you found the parts at that price and how much the upper ball joints/controll arms are as I still need to replace mine? Thanks and hope this helps.