OP, the bottom line to your question is just buy a new machine or from a very trusted Pinsider like NJGecko or eaBundy that is WELL known here for doing quality work.
Things will break, yes, it is inevitable. But when things break, typically the repair is not astrophysics. It is decently rare that anything goes bad behind the translite (especially with LEDs installed and the temperatures go down a good 20-30 degrees Farenheit). If a coil sleeve needs to be replaced to make the coil more powerful or responsive, a switch needs adjusting so the ball properly triggers it when rolling over, a bulb burns out - those things aren't too bad.
Bumping up a bit in difficulty, if a coil shorts out (read: constantly on and is blowing a fuse), a light needs to be re-wired because changing the bulb didn't fix it, an opto needs to be tested to verify it works, any soldering job where you are taking out bad, broken components and replacing with nice new working components, or a ramp needs to be flame-polished because the plastic is starting to get loudy or show "ball streaks" or you need to take things off the playfield to get a THOROUGH cleaning done - yeah, these things suck - but they're not impossible. They will happen, but traditionally, they aren't going to "just happen" the very first week you own the game.
Bumping up a lil' bit more, you start smelling electrical burning somewhere. You open up and wires are starting to burn, electrical connectors are "getting crispy" and you have to re-pin an IDC connector, or a transistor is shorted and needs to be replaced, or a UXX (where XX = some number) chip burns out and needs to be replaced - basically anything in the backbox - yeah - it may happen, but the chances are decently rare, especially if the temperatures are down, and your game is properly taken care of.
All out "oh hell...." difficulty is doing something like re-applying cabinet decals, removing and stripping a PF to be re-clearcoated or 20+ year mylar pulled, or swapping cabinets entirely. Life will probably suck then because you have to pretty much fully gut a machine to apply new decals or swap cabinets. Will you see that level of difficulty? Only if you want to at that point.
So, do what is best for you. I've been doing this for 3 years this March, and while I by FAR do not know everything, there is a learning curve, and I am happy with where I am in this hobby. Believe me, if I have a chance to fix things in this hobby, ANYONE can do it if they apply themselves. This community is AWESOME, and it is definitely not who you are but who you know. The more you network and get to know people (read: going to pinball get togethers and meeting people face to face), the more you empower yourself to learn and help others. This is NOT a hobby you can succeed in alone.
A friendly word of advice: make sure you know how to solder and use a DMM. Trying to own a pinball machine without either skillset is like watching a snake try to work in a kitchen.
Good luck!!