Most police guns I've seen come with factory-installed night sights, when they have night sights. That's certainly true of the S&W and SIGs I've been around.
(My S&W 4043 has bright factory night sights, and its several years old.)
I've got PTs on one of my guns, and they're doing fine. But I've had one pair fail quickly, and several friends have sworn off the brand completely. (Their problems were a few years ago, and PT latter acknowledge a bad supplier, and replaced many bad sights under warranty.)
Sometimes a lower price means comparable quality at a savings. Sometimes a lower price means you got what you paid for.
Whatever you do, get something with white surrounds around the tritium vial. Without that, the sights are only marginally effective in daylight.