Hi Matt,
I second what Pat said above ^. The social worker at your CF center should be able to help you find and apply for assistance programs.
Also, you can check out the Cystic Fibrosis Patient Assistance Foundation:
http://www.cfpaf.org/
They offer copay assistance for many CF drugs including Tobi and Hypertonic Saline. You can make up to 400% of the federal poverty level and still qualify. They have a screening tool on the website you can use to see if you qualify. They currently assist me with my copays for Cayston, Pulmozyme, Hypertonic Saline, and Pancreaze. Everyone I've talked to there is very knowledgeable and helpful. If you have any questions you can give them a call, if you don't qualify for their assistance they refer you to other programs that may be able to help.
Good luck and take care!
Autumn 32 w/CF