They say that on average 400-500 miles is a good bet for running shoes, but for myself it's only about 300-350 miles before the aches of worn out shoes start to occur. It seems that shoes are one of those items that you definitely need to spend some more on to get anything that is going to last. I imagine that the same is true for hiking boots but have not gone through enough of them them to speak from personal experience. What I'm wondering is how many miles should one expect to get out of a pair of hiking boots in the $100-$120 USD price range?
This is wildly dependent on your gait, the terrain the temperature and climate in which you hike, your ability and rigor at cleaning and taking care of the shoes.
There will likely be some brands that will last longer on your feet, but that is not necessarily only the price range that determines this. There are some "shoe laboratories" that will analyse your gait and find the right shape and type of shoe for you - but the availability of such where you are is unknown to me.
IMHO 300 miles (~500 km) for the pair sounds a bit short. That's only 50 short-ish 6-mile (~10 km) jogging trips.
Terrain makes an enormous difference. I have a pair of light boots that have lasted me nearly 10 years and probably over 1000 km with many more to go (normally with a backpack, quite often over 10kg). I used to have the shoe version - identical except for the height of the ankle - as well. The sole was quite worn after a few hundred km and the only reason they got anywhere near 1000 km was that it was for lots of little walks, for which anything would do. My bag then was rarely over 5kg. The difference is that the ones that wore fast were used almost always on paved surfaces, while the long-lasting pair are used on the typical mix of hiking terrain: some rock/paving but lots of dirt.
I've always found sole wear to be the limit, and can get away with almost any shoes so long as they fit properly. If you find you need a more specific sole, then wear will become much more of an issue.
A couple of factors from my own experience are:
Pronation - I over-pronate slightly, so the outside of my heel gets worn down more quickly than the inside. When it wears past a certain point, I find myself rolling my ankle more than usual and end up buying new boots.
Sole material - The softness of the sole material has a large impact on the longevity. Soft "comfort" soles of course wear out a lot faster than harder soles. This of course is why running shoes wear out quickly. Of course, the downside is that harder soles can be a little less comfortable, but that's something you'll need to weigh up for yourself.
I'd agree that 300 miles (30 decent walks) are on the low end of what you'd expect. I'd advise you to take a good look over your worn-out boots and identify where they've worn out the most, then buy something that addresses those points. Or take an old pair into a reputable store and ask for guidance.
I seem to have a different answer from others.
I’ve worn Asolo or zamberlan full leather boots for 40 years, pretty much every day. I walk a bit over 1000 miles per year in them, 200 on trails and 800 in daily work/home use.
The soles last 3 years before they are slick, so 3000 miles. A resole costs a little over $100 and gives a little over 1 year more before something goes wrong, so it’s a toss up compared to buying a new pair of $300 boots.
I am not meticulous about care, my shoes are not pretty very often.
I can’t imagine buying boots every year like everyone seems to suggest, rating the life at 500-1000 miles. Mine are still mostly new at that point. I don’t get it.