this kit use to be $2500-$3000.00 new, it was the only bolt on kit you could get with any increase in travel at the time.... I have this same Lift kit. (CST made one for a short time, it was basically the same kit)
If he really has new upper, lower ball joints and new tie rod ends with brake lines. I'd say its pretty fair priced.
my only concern is where are the tierod extenders? is that just a longer tierod sleeve? the arms are 2.5" wider on each side so you got to have the extenders and mine do not look like that. Also my bump stops do not look like that either, but they look to be similar thickness.
also make sure you have the right spindle for that lift, at the time I believe Fabtech made 2 different kinds of spindles, 1 didnt work with that lift. (contact fabtech, they seemed helpful when I needed hardware)
Lift should net you 7.5" lift, and I offroaded mine pretty hard in sand, it did very well, to the point where I wanted to upgrade the leaf spring pack in the back.