Last time I put a set of tires on our Mazda I figured it was time to replace the ten year old (Denso?) sensors. If I didn't do it now, they'd be gone before the new tires went. I ordered a set of four genuine Mazda sensors for $55 (for the set) online and the tire shop installed them for free...but hit me up for $25 to do the reprogram.
For our toyota, the sensors will be more. I'm banking on about $100 for four of those puppies (Denso?) but will hold off until this set of tires goes, proably about a year from now.
Sounds like your friend helped their commissioned service writer and commissioned parts counter staff make their upcoming boat payments. Your friend should get a quote from another dealership and call the service manager. Even at $100 a sensor (typical excessively high dealer nonsense cost) sounds like he or she got hit for a few extra benjamins.