The J8 kit turns the 4 door JK into what you see...without the lift/ bumper/ etc.
They have a weld in kit and a bolt in kit. it is very labor intensive. My local dealer has done 2 and sold them both for over $50K.
The JK8 kit is $6K. Add lift/tires/bumpers add labor/ bodywork $18K. So for an additional $24K on top of your $35K+ 4 door JK, you can have one.
We looked at building one through a partnership with another company and selling it. it is a ton of labor involved!
If you want to see what goes into the build, shoot me a PM and I'll send you a bunch of pics.