It took me some time as an amateur mechanic to gather the tools needed to do an entire bike, and at 55 years I'm still missing a few. Maybe start with certain parts and concentrate on those and let the shop do the others. And $50 won't get you much of an overhaul. If the wheels are cone and bearing type as opposed to sealed I'd start there as cone wrenches aren't expensive, but be careful when re-packing. Read up on how it is done and how it should feel (which you can't really read, it helps to have something to compare.) BBs are similar if they are the old square taper but require many more tools as Gene points out.
The tools last forever so don't hesitate to buy them if you think you'll ever use them again. I repacked a BB for the first time in 20 years just last year, and I had all the tools necessary on hand. And that BB is now smooth as silk.