Cost of replacing exhaust system for 97 Altima?

Newbie with an urgent question here. We have a 97 Altima. Drove it on a long-distance trip carrying a lot of weight a week ago. Midway through the exhaust started making incredibly loud rumbling noise. We managed to make the trip and brought it to a Midas. They told us the exhaust system is pretty much all broken, and need to be replaced. They ask for around $700 for the job. I know next to nothing about how this price compares to other repair shops. Is this price a reasonable estimate? If not, any recommendations on where to get a better deal? Sorry but we’d rather not do DIY. They also said we should replace the right-front axel, which would cost around $300.

We are planning on selling the car soon, is it worth the cost to replace the exhaust system? Thanks a lot in advance.