First, check with your health insurance company. Many insurance companies will cover a breast reduction if you've had a history of health related problems. Be sure to keep track of any physical therapy, chiropractic or other doctors you've seen due to back and neck pain. A proven pattern of neck and back pain, and evidence you've tried to find alternatives to surgery, will help your case.
Short of that, try a "Minimizer" bra. It can make you look up to 2" smaller.