I'm about 5k into my d60's (front and rear), but that includes new dedenbear knckles, 5.38 gears, front detroit, rear spool, master install kits, kingpin overhaul kits, spindle kits new studs, lug nuts, coils, and the wheels/tires. I still have to get the gears installed and buy all the link components. I will probably be around 6-7k before i can say i'm finished. What i planned on doing 2 months ago with a d44, has accumulated into d60's and not even starting any of the heavy duty work yet.
btw, the 60's (79 f350 kingpin and rear 30 spline) cost me 1k. My 76 d44 8 lug lp and rear 30 spline 60 cost me 300.
so 2-300 for a kingpin d60 is something you should jump on. 2-300 for a balljoint d60 is still something you should seriously consider. the kingpins average about 1k and the balljoints average 5-600