The lift itself isn't more expensive, you just have to buy an aftermarket drive shaft.
I believe it has cv joints instead of u joints.
If you have a 4 door you are required to buy a torsion bar crossmember as well.
Like the RCX 6" kit:
Lift $1000.00
Sway bar end links + $$
Torsion bar crossmember $200+
Auto trac drive shaft about $500
It's about $1700-1800 added all together
I don't remember the exact prices of all the extras.
I have a '98 4 door with auto trac and researched lift kits earlier this year
But tossed the option out of the window and opted for a body lift
I haven't researched any other kits that are $1500+ but they may come with the extras.