From what I've seen, none of them are particularly inexpensive. My dealer recommended the TireMinder system. I've been happy with it so far.
Rob
U.S. Army retired
2020 Solitude 310GK-R
MORryde IS, disc brakes, solar, DP windows
(Previously in a Reflection 337RLS)
2012 F350 CC DRW Lariat 6.7
Full-time since 8/2015