Yes, I'd say there's plenty of room for wiggle in the price considering its age. It's clearly not moving fast. But you might be better to negotiate for thrown-in merchandise rather than price. Maybe a front rack, panniers, water bottle cages, helmet, blinky light for the rear, a dozen spare tubes, some clothes, chain lube, better fenders, a pump, a bike computer, shoes, etc.
Not much on a bicycle deteriorates just sitting there indoors. You might not need to replace anything. If you plan to do a lot of loaded and hilly touring, you might want lower gears. Otherwise, it might be fine as is. Ride it for a while (at least six months, maybe even a few years) and see how it goes. See how well you can adapt to the saddle.
What else you might want to do depends on what you plan to do with it.