unfortunately I need more information to answer your question. There are several parts to an exhaust system and they all have different costs.
Is it rusted out?
you can find aftermarket exhaust shops that will do pretty inexpensive repairs. Places like Midas or Meineke.
anywhere from 80 to 700 parts and labor.
mufflers are usualy around 40 to 60 bucks installed and these places, but you will often need a pipe or two. Pipes vaery in price from 40 to 250 dollars.
Also, there is a catalytic convertor on your car that is around 200 installed if needed.
And of course you have an exhaust manifold too, but it doesnt sound like you are asking about, and that is NOT a typical exhaust repair.
Are you asking about performance exhaust systems? probably around 600 to 900 parts and labor.
Hope this helps.