If its a viral infection, you won't need antibiotics anyway - the best thing you can do is to drink lots of fluids, particularly hot fluids to help loosen up the phlegm in your lungs. I also like to use an expectorant, because my lungs were damaged by pnemonia when I was young and I have a hard time clearing out chest congestion without it. Doctors often prescribe asthma meds to people with brochitis for the same reason - to help them with the lung clearing process.
If you have a bacterial infection and need antibiotics, there really is nothing you can substitute for it!!! If your illness worsens, is accompanied by high fever or continues for a long period of time, please, don't take your life into your hands for the money.... your life is more important than any amount of money.