Use a soup can, some sheet metal screws and some muffler tape, that should be cheap enough. But don't forget to take the soup out of the can first and cut both ends off.
Pull it off and get used to the noise. Muffler tape will do nothing but waste the money you spend on it. The soup can trick has a better shot at holding until you get the scratch to fix it properly, but if the bits you are holding together are too soft it will just come back apart right away. More often than not, by the time that rusts apart, the muffler is junk too.