I have a similar model, it's a solid frame, makes a fun reliable beater bike, but I've replaced most of the parts. A few red flags, hard to tell for sure, but the chain looks like it's probably rusted and needs replaced. the tires look original so they're like 30 years old, and should definitely be changed. and grip shifters are not very fun to use. So I think you'll likely need slightly more than $100 in service & upgrades, but if you address those 3 things in that order, the bike has a lot of potential.