Yep, timing belt is done by mileage, so it may have already been done. Check your manual for the recommended maintenance for that one. Mine's close to needing its second replacement (!) and the car is 12 years old, 170k. But at least its a belt and not a timing chain - I think it cost a small fortune to replace that in my old car ($700? maybe more? and the mechanic screwed it up and eventually "totaled" my car b/c of it).

If you're tight with money you can probably wait on the water pump, especially if you aren't about to take on a long-distance trip. Brakes are iffy - you can likely delay those a little while if you need to split up your costs, but I wouldn't wait too long.