If $100 is the top-limit of your budget, they're good bang for buck.
I haven't had any durability issues with them (yet), and I've been using them almost daily.
I brought them into a headphone bar to compare to other headsets, including (because I carry them everywhere) my Bose Soundsport open-channel earbuds, which somehow sounded comparable and are much more comfortable (though have zero soundstage... because they're earbuds).
While the HiFiMAN HE-350 is a noticeable step up from most $30-50 headphones (which I had previously been accustomed to) in terms of cleaner audio and relative flatness, no enthusiast that has listened to them has agreed they're worth purchasing, even as an entry model to quality sound. I find them moderately uncomfortable over long periods of time, applying significant pressure to your upper jaw/temple, even on maximum size - and they give most other people instant headaches.
I'm far from an audiophile, but while these have served their purpose to me as an introduction to purchasing "higher-than-what-I-had"-end audio equipment, they're not enough of a departure from the $30-50 crowd to warrant more than a year or two of saving up to get the next significant (and hopefully more permanent) step up... looking at you Senn 599!