A 1,000 bucks? I'd tell prospective buyers to kick rocks, no offense. People are asking and getting $$ just for tanks in good condition. Even if the bike you described needed new brake fluid and some reasonable caliber work, you still couldn't justify a $1,000 sale price. Getting new tires is almost a given, even on bikes in great shape. If the tires still sat over time, they could already be passed the manufacturer recommended run times. When I look at used bikes, I am never surprised that they need new chains/sprockets and tires?
People always overlook this; carefully inspect all bolts and fasteners. See a lot of stripped or 'cammed out' bolts etc? Yeah, the owner showed little patience or attention to detail. If that is confirmed, can you trust that critical and expensive internals were not neglected?
Post detailed photos here and get some more insight because I'm confident you'll get more help. Good luck!
Jeffrey Alexander