KYB Strut SR4472/4473 or SR4472K/4473K(Leveling) ?

Anyone have experience with the preassembled leveling kit option? Stumbled upon it on Rockauto. Son needs fronts replaced (probably stock). Currently has an old spacer ruster out on there. Substantially cheaper than Bilstein prebuilt. Is Rockauto really this much cheaper than all the suspension websites? I can buy the SR4472k/4473k combo for $449 out the door. Just doing the non-level is $320 vs. $500 on shocks websites. It appears they only come preassembled, just can't believe the price difference.

I've been looking at suspensionlifts.com as well, but the reviews are really mixed. Appears many times they come with the top hat not aligned properly or wrong springs, etc. They have a Bilstein 4600 or 5100 with stock springs that isn't too much more.

He is never going offroad with this and will be on the highway 90% of the time