I fixed that on my son's QX56. You have to loosen a lot of stuff like the bumper and fender well. There are step x step instructions on the internet. After we got the full fixture out, we removed the bulb units, drained the assembly then ran a hair dryer through them for 30 minutes. Apply silicone around the seam between the two halves then hold a vacuum up to one of the bulb holes while blocking the other bulb hole. Be CAREFUL not to collapse the entire unit. You only want to suck silicone into the seam. Let sit an hour or two then re-install.
Junkyard is your only cheaper option that I am aware of. There are some knock-off lamps for many vehicles these days that are cheaper, but if the are articulating lamps and HID's it's just flat-out gonna be expensive