Let me share I picked up the Seek unit from https://smile.amazon.com/gp/product/B00SSZ5KQI/ which came to $195USD to my door.
As to why this is really simple. To get the price down it has to be mass produced and for most phones they are in a price war where every dollar counts so no major maker will put these features in just for the few that want it.
In my case I really wish I could have had this Seek unit 10 years ago as I was finding heat leaks with a laser spot thermometer. This would have made the work so much easier. Even without the IR camera I still did a good job as our highest winter gas (heat) bill was 300USD. The neighbors that didn't do such work were reporting 800+USD for that same month.
1. How come there no smartphones with Infrared Imaging (not infrared blaster) built into them, or at least ones that are not excessively overpriced? Buying a separate IR imaging device can be just as costly as high end smartphones. Not a good choice.
2. While trying to find a decent phone I've noticed that they come with a mundane set of sensors in them. You would think somebody would have come up with a more interesting set of additional sensors by now for doing different things. What has been your experience?