As it happens, my Dell s2415H has speakers, and when I checked, it also has an output jack that works with my JVC Gumy.
I believe plugging in those earbuds cuts off the monitor's speakers, but I can't be positive because the audio output from this PC goes through a subwoofer that was still booming away to a jazz tune, and I don't want to mess with the connections.
So Dell might be a good place to look, if their monitors meet your other specs.
Most decent monitors have a headphone jack. Obviously you first need an HDMI or DisplayPort input, and I noticed that most monitors with an IPS panel have a headphone output (presumably because they're not complete crapola?). My searches showed that LG monitors almost always include a headphone jack (regardless of whether or not they have built-in speakers).