Do it your self.
In the past I was not as well equiped as today to do my own repairs, I have my own 5 HP air compressor and air tool. If it is your pipes that are rusted, you can repair them with small kits fron Canadian Tire. After 4 or 5 of these repairs you will find it cheaper to replace the pipe. If it is the muffler that is rusted then you can do it yourself by just removing 2 bolt and replaing the gasget and the mufler itself. The plrice will depend on the car, if it is a popular model then it can be from $80 to $150. for the parts.
These days it is worth it to have your own well equiped shop, even if you only use it 2 or 3 times a year. After spending about $2500 for the repair equipment I figure I am just about even. Adding in the repairs I have done for friends and family, I am way ahead.