Many people with COPD also have sinus problems. Using a nasal or sinus rinse program provides a cheap and effective method of cleaning out the excess mucus.
The links are for the products that I have looked at or use. I have used Nasal Rinse ($10) and RhinoFlow. (about $150). You do a search on Rhino Flow and find it for less on the internet.
Rhino Flow by Respironics