Pardon the rapid posting, but I like shopping 
…
A quick search finds actual Digital Pressure Gauges for ~100psi to be in the $400+ range, and perhaps double or triple for wireless.
http://www.newark.com/noshok/1000-145-2-1/digital-pressure-gauge/dp/34P2821?COM=Embedded
But even this high-pressure sensor itself is $265!
http://www.newark.com/vdo-imt/3296075001/pressure-transmitter-0-10bar/dp/71C5563?COM=Embedded
Or this, etc.:
I guess the questions remain:
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Can “one-off” pressure-voltage sensor part be found with NPT connection and sufficient range, so that Arduino project could be built? Honeywell, etc., etc., manufacture this component. And lots of sources in China. Just hard to clearly understand the specs. There are lots of digital sensors with ICs, but I think these are mostly for low-pressure use (barometric, altimeter).
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Can a non-wireless digital gauge be found for a reasonable price (? $100, $400 ?) that can be converted to wireless?