Recommended replacement muffler

Vehicle Information: Model (914/4, 914/6): 914/4; Year: 1974; Engine (type, size, modifications): 1.8 L; Total Mileage: 75,000;

Getting this car running after it has been sitting for 20 years. The original muffler is rusted out. I see a new original style costs ~$700. What is a good alternative for less money? I just want to commute in this car during the summer, no plans to race it.thanks