I have been using the cheap, under $30 TPMS for 5 years, even use them on the wifes car which has factory system, but only indicates low tire, not which one or how low.
The cheap ones only go to 55 psi and the new to me Roadtrek has 80 psi in the rear tires. So bought the Tymate system. have not used it yet so no opinion on it. The cheap systems tend to last about 2 years and are not NASA accurate but never fail to report an issue. The Tymate is easier to program than the ultra cheap ones.
https://www.amazon.com/Tymate-Tire-Pressure-Monitoring-System/dp/B085C2HMQP/ref=pd_lpo_2?pd_rd_i=B085C2HMQP&psc=1
