The main round button (push/enter) on my navigation was missing when I bought my 2002 xkr. I thought I could easily obtain one from the *********** but that is not the case. of course they want you to purchase a new nav system instead of the button. The nav still works. I just have to stick my finger in the hole and push the stem. I just dont like anything missing from my car. Does anyone have one for sale or know where I can buy one?

 

I've seen the whole navigation screen (working) with the button sold on eBay buy-it-now for as low as $59.00 with free shipping. I've also seen broken units with the button sold for around the same price. Just keep looking, not all go for $199-$600. I'm pretty sure that the button will not be able to be bought separately through Jaguar or Alpine, and am not aware of Alpine having that button on any other of their products.
I think you could fabricate one, but it will take a lot of trial and error - I would find a generic knob(s) and drill it. Once you figure out the right depth and diameter, I'd probably try to superglue a toothpick in there to give it the correct shape so that it doesn't twist (so it fits correctly on the half-moon rod part).

 

I have had at least 40 customers who replaced their navigation monitor with the three gauges. Maybe one of them will come forth here and offer to sell you their old monitor.

 

I have the same situation, so there are two potential customers for a Nav knob if there are people out there willing to sell their unused screens.