I wouldn't call a still-on-the-road 17 year old car a "lemon".
However, it appears you are catching up on deferred maintenance, just like if you bought a house with a 25 year old roof, a 12 year old water heater, and a 25 year old HVAC system. If you bought such a house, it would seem like all those things were hitting at once, and you might even start to expect similar expenses in future years. No, actually you just bought a used-up roof, water heater, and HVAC. Hopefully, the price of the house reflected these deferred maintenance items. Next house, you'll pay close attention to what was recently replaced and not, and budget accordingly.
The failure points on your Corolla are all related to deterioration of rubber/plastic on stress/flex areas. I bet the CV's went bad because the rubber boots around the "gears" rotted off and exposed the parts to road grit. The door handles are just plastic deterioration. The AC is leaking from the rubber hoses.
With this in mind, you now know the next failure points: radiator hoses, vacuum lines, brake hoses near each wheel, maybe even windshield fluid hoses.
Factories have predictive models to anticipate parts failures and replace working parts before they are likely to fail. It's how they reduce downtime, despite often working with complex assemblies of 30-40 year old equipment 24/7. If "downtime" is what you want to avoid, while still enjoying the low costs of an older car, you should do preventative maintenance too. So, while you are replacing the A/C hoses, replace the nearby radiator hoses too. While you are doing a brake job, replace the rubber brake fluid hoses. Put in new wheel bearings and grease any time you get the chance (e.g. if you're replacing rotors) - they're cheap until they fail. While replacing spark plug wires, consider also replacing vacuum lines.
If you're doing your own work, the added costs of such PM is negligible - your hands are already dirty, might as well replace 2 parts instead of 1. If you are hiring a mechanic, you can use PM as a negotiation point. "So front rotor replacement will cost $350... would you throw in new bearings for another $30 plus cost of parts?" The mechanic knows s/he will already be looking at the bearings when he takes the rotor off, so s/he is likely to take this offer. Then you just prevented what recently happened to my buddy when one of his front wheels ground to a halt on the interstate.
Shop for parts on the internet. If you can score a fuel pump for $35, grab it! Then you'll have one less thing to worry about.