I'm intrigued, what's the range that these machines go for?

Really varies, but generally prices have gone up with time. I would say a non-sought-after older title might be available in the $500-1000 range, but it would likely need some amount of fixing/freshening/overhaul. We used to joke some games would be worth "$10k by xmas" but games today have made that figure sound cheap, lol.

Realistically though, you could get a beater that's working for around $1000-2000 +/- but it really depends what era you're interested in...Newer games can run closer to $4-6k+ used, and $7-15k new. Believe it or not there are several companies making games nowadays, though there was a time where there was only 1 left (Stem Pinball)...!

Are they easy to fix and maintain, I guess something a hobbyist and collectors would learn to do?

Not easy per se, but if you understand electronics it's nothing too crazy. You need to be able to solder. There's tons of helpful people online at places like Pinside that take pleasure helping others fix their games (I've been among the helpers for a long time, after having received so much help when i got started--i try to give back 🙂)

There are many aftermarket replacement cpu boards which solves one of the biggest challenges back when i started...repairing circuit boards is substantially harder and takes a lot more know-how than fixing up the mechanisms on the top and bottom of the playfield. With many solid choices on the market, you can replace all the old circuit boards, leaving you to focus on the playfield where the action is.

Parts are available at a number of distributors, my favorite being The Pinball Resource in Poughkeepsie, NY. Steve Young has single-handedly kept pinball alive for the world, his operation provides so many parts and still do to this day. They don't accept card payment either--strictly check or money order! Old school as fuck, i love it. Newbies come along and start bitching about his ancient website and how he needs to get with the times etc etc. He's pushing upper 70s early 80s from what i gather--and he's still moving forward every day producing rare or impossible-to-find parts in addition to droves of standard replacement parts as well. Nothing but respect, and when he's gone he'll leave a hole that can't be filled again. Feel free to reach out if you'd like further info or assistance getting into the ~~addiction~~ hobby 😅