Good luck with your shopping and welcome to Subaru. If it makes you feel better about what you are looking for, I put my family in almost 20 year old subaru with near 200,000 mi or more, as i am not afraid of what to expect with them (as i have had very many) and i do all the maintenance myself. Recently, I provided my woman with a 800 dollar 96 impreza 185,000 mi, original to Idaho, as i am in Wisconsin, and a rust free car is something to appreciate. All the car required of me was a PCV valve and an oil change. I did have to replace the master cylinder, but i have less than $1000 into this car, and almost that much into a 92 mazda i replaced it with.
I also scored a 98 legacy outback with 132,000 mi with a skipped timing belt for 550 dollars. I repaired it with spare parts, and now it is good to go with a new timing belt for another 100000 mi. This is becuase the 2nd owner never did the 100,000 mi service after buying it from the first owner who sold or traded the car before the service was due. The timing belt skipped because one of the idler pulleys failed a bearing at 132,ooo mi. This is a win for me, getting a car for cheap, and a win for the car, since i saved if from junk (this is the limited with premium sound and leather interior!) Ironically, this is one of the nicest and lower mile used cars i have ever had out of almost 100 cars in my lifetime, and probably 50 subarus by now (althought a lot of them were 300 dollar rust piles) By this math, i am better off with 2 or 3 used subarus laying around than one new one, as i can resort to the 2nd or 3rd car as a backup i the first or 2nd one goes down for maintenance (the usual alternator or starter, routine repairs)
The moral of the story is here: A lower mile car is approaching the 100,000 mi mark will be due for its major service interval. A car with more than 100,000 mi may already have the work done. This means a car with 80,000 mi is due for service and will get you 20,000 mi out of it. A car with 120,000 mi
(assuming the 100,000 mi service was done) will get you 80,000 mi before it's due.
Take this into consideration when shopping around. And don't be afraid of the miles, as these subarus routinely see towards 300,000 mi and more as long as you don't neglect the routine services or let it run out of fluids.
One more thing to consider is who does your maintnenance. With subarus, the design is much different than conventional autos with horizontally opposed engines and AWD layout, the car is basically a mirror imigae of itself if you cut it down the middle. With whomever does your maintnenance, you will find that either the mechanic knows nothing about the platform, or the the specializes exclusively in the platform. Common conventional auto knowledge a lot of times does not apply with subaru. You did right by joining this forum to learn about Subaru.
Either way, whichever way yo go for newer or more used, you can do your part simply by checking the oil and the air in the tires to avoid reliability problems. Change the oil from 3-5000 mi, add as necessary (you may need to top off a quart between oil changes). Consider 5w40 wt oil if the car has more than 100,000 mi, especially with turbos, synthetic blend or full synthetic 0w40 oil.