First advice: Don't do it.
Okay, now that we're done laughing out loud in denial..
What the others have said is solid. Play on location as much as you can. LOTR is a great system - I blame it, and my wife, for getting into this hobby (see here).
Second advice: You won't be able to stop at just one.
Yeah, I laughed at that. In denial. But the reality was, I wasn't as much into LOTR as the wife was, and I wanted something to play that was more interesting to me. "Hey, let's go pick something we know is hard, will make me work for a score, force me to get better. TSPP!". Found one locally, from a coworker even. Didn't make me a better player, but I did play it quite a bit. Ultimately, I don't play well enough to enjoy that game long-term; maybe I'll re-acquire it down the road when I'm a better player.
We did have a few advantages that helped us get into this. Friends already in the hobby, willing to teach. Pinside. Space (we had rented warehouse space for other purposes). Cash. This hobby's expensive, and you never want to finance a hobby. Lastly, while this area is not a mecca for pinball, there are some bright spots - favorites being the Pacific Pinball Museum, Free Gold Watch, Phoenix Games. pinballmap.com is useful to find pins on location. Just keep in mind that a lot of location games are not well maintained. These locations gave us opportunities to actually see what we liked, what we didn't like. Our collection is mostly but not entirely A list; and cater entirely to what we found we liked more than anything else.
None of this stuff is an investment. We haven't sunk money we can't afford to not recover. That said, I don't expect to take major hits on anything; and I don't expect to get rich of anything either. I consider depreciation to be effectively the cost of renting entertainment.
Top games will require less repair - but command top dollar. You'll need to ask yourself about where you stand on that. Even top games will require maintenance. You'll want to learn to do at least the basics. And learn who you can lean on locally for help that's beyond you - and determine how much you want to lean on them, versus being self reliant. The folks here on pinside are pretty good at helping out those seeking to help themselves.
Don't overlook "B" list games. Seriously. The cost deltas between A list and B list are staggeringly stupid. There are a ton of fun options out there.
All that said: If you can have just a single game: LOTR is not a bad one. I do play mine. The wife plays it more. The guests play it a lot_. It isn't so complicated that a 7 and 11 year olds will be lost. But as they learn the game, assuming they really embrace the hobby, they'll start to get the much higher and insane scores. I'd encourage not comparing scores with others online; just keep a local scoreboard . Compete with each other; work to get better; but don't get bent if you can't make billions on LOTR. Most important part is to have fun getting better at pinball, and exploring what the game has to offer.