1999 Chevy Suburban AC Leak in line to the rear unit.

Air Conditioning problem
1999 Chevy Suburban V8 Four Wheel Drive Automatic

I have a leak in the AC lines that go to the rear cooling unit. I was quoted by a chevy dealership of a $3000-$4000 bill to get it fixed. That is insane. There has to be a way to fix it at a much cheaper rate. It is a small hole in an aluminum line. There must be a fix out there rather than the $300-$400 cap that they had to offer that does not let the refrigerant get back to the rear unti. Please help as this SUV hauls kids in town and the AC is important for my sanity