Picture 2 and 4 shows the piece that the bent medal bracket bolts to. It's the machined stud that screws into the tow hook mount. That threaded stud is probably the majority of the cost, not the bracket that bolts to the plate you are referring to.
I'm not sure if the Z has a pop out panel on the front facia for the tow hook. If it does I'm sure they'll use that method and the kit will be similarly priced. If not maybe it'll be cheaper using some other way...? I'm sure you could call/email them.
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