A bit of research revealed that most people with this problem get a stand-alone climate control unit from a wreck that did not have OEM Nav. That unit goes in where the radio is in my QX4 leaving the double din hole above for an aftermarket "what ever you want".
Cost looked like at least $500 or more going that route, so here's what I did to salvage the OEM unit. My son is a self taught electronics tech, so he took the unit out and disassembled it down to the backlight. Since we had no way to know if it was the bulb or the circuit that powered it, I took the bare bulb to a local neon sign shop. The guy there was real helpful. He tested it and pronounced it dead, but observed that he did not stock the small 2mm glass tube that the bulb was constructed of, nor did he have the supplies to make a cold cathode florescent tube. While he couldn't make one for me, he knew exactly what type of lamp it was and had the correct power supply to test it.
My next step was to go home and search the net for info on CCFL (cold cathode florescent) lamps. I found a place that made some very similar lamps, just not the exact size C shape I needed. To make a long story short, I had to order a minimum of 10 bulbs to get a custom one made to match the burned out one. Total cost about $200, which I figured was not to bad to get the Nav/Climate unit fixed.
Now I have 9 spare bulbs. If anybody would like to buy one, private message me with your email and I'll get back to you with a lot more info. The bulbs are complete with leads, the correct connector, insulators and spacers. Installation is plug in, no soldering required.
Maybe we can lower your repair costs and mine too.
AceEngineer