I have a '95 Corolla, which is basically the same car. I'm within spitting distance of 200k miles. I'm probably a bit more mechanically inclined than you, as I do (almost) all my own car maintenance and repair. My car is actually due for a timing belt as well--I just have to find an open Saturday to work on it. All that being said, here are my thoughts:
1) Get in the habit of checking the oil every time you fill it with gas. Figure out exactly how much oil it's burning. Do the same for your transmission fluid. You're not doing anything else while the gas pump is running, so you might as well, right?
2) Syonyk is probably right on the thermostat--I replaced mine within the past year or so. It's actually an easy fix--just a couple of bolts in a mildly tight spot--and the part is cheap. Like <$10.
3) Brakes are a normal maintenance item, and getting a new-to-you car won't help you avoid that cost. (it might delay it a bit)
4) Squeaks and rattles are normal in an old car. Mine does it as well. I have a folded-up napkin wedged between the dash and the windshield to stop a buzz there, I have a penny wedged between the dash and the A pillar to stop another buzz, and the rear-view mirror rattles too, although it's genuinely broken. Oh, and one of the front reflectors rattles around inside the bumper.
How willing are you to learn how to do car maintenance and repair? In my opinion, it's a lot simpler than it at first appears. If I were in your shoes, I would:
1) keep the oil topped off (and check at each fuel stop)
2)
change the gear oil in your transmission
3) get new brakes (Not too hard to DIY--harder than the thermostat)
4) do the timing belt yourself, or not at all. It's not worth paying a mechanic to do it for a car of that age. It's a time-consuming job to DIY. If you don't want to pay for it, just drive it 'till it goes boom.