And I'm sure there are plenty of ~6" Android smartphones available for less than $500. My point was for a device that will be used "every 19 minutes" for years

And I'm sure there are plenty of ~6" Android smartphones available for less than $500. My point was for a device that will be used "every 19 minutes" for years, and it's network access will cost several times the price of the hardware, I don't see why $500 vs. $400 so important. Especially if it means lower quality hardware in a computer that gets a LOT of abuse (compared to a laptop or desktop). If you want a Nexus 6, you need to buy a Nexus 6.