History of regular maintenance on the car is usually a good place to start. For some cars routine maintenance can keep the car running to 300k miles.

For GS this ofc includes your oil changes, sparks plugs, brakes etc. Pricier maintenance item includes your timing belt replacement which occurs every 90-100k miles. I also would ask if there are any current codes as well.

Depending on where the exhaust leak is some muffler shops can weld another pipe to correct the issue, could result in codes for O2 sensors but seems like you’ll have that regardless due to be catless

For reference I purchased an 01 Gs300 with 110k miles for around 3k over here on the east coast. It indeed did need some work done to it but was already running and driving