Park used to have a better list of tools, less so now, but still some decent repair help. There's plenty of internet info (Sheldon Brown, etc.) and lots of simple how to books (Bicycling Mag, Lennard Zinn, etc.) that all have tiers of tools. Also maybe some coop places where you can share tools, or a bike maintenance class at an REI, etc.

You're probably going to need <$50 of bike specific tools -- some a good general investment (cone wrenches, chain whip) others possible specific to your older bike (BB and cassette tools). You'll need to buy cables, tires, tubes, maybe tape, grease, ball bearings, perhaps some races, etc. depending on how rotten all is, probably in the $50-100 range. At the end of the day, this is eminently do-able but also likely in the same ball park where you might find a more modern, capable, and perfectly functional used bike. Reach your decision point on that before you go hunting for some archaic tool that a newer bike wouldn't need, although many of the simple cheapie all-in-one bike tool sets will come with much of what you need.