I just bought a TST system at a streetside vendor in Quartzsite. I paid $239 for Receiver, charger, suction mount, and 4 sensors. New sensors are $35. I drove from Quartzite to Las Vegas yesterday (4 hours), and the system seemed to work just fine. I felt a lot more secure, too.
This was a TireTraker TT-400C system with a 3 year warranty. The vendor was RV Special Things (rvspecialthings.com)
While talking to the saleslady on Tuesday, she told me that she had a lady who had just come to Quartzsite from Riverside, County, Ca. who had a blowout on the trip. The report was of over $2000 damage to the rig, and the floor broken through. I had just made the same trip from Riverside County to Quartzsite. She told me this after the sale. I didn't tell her where I had come from.