TPMS Sensor replacement question

Greetings experts ! I need to replace the tires on my 2008 Grand Caravan, SXT, 17" wheels,

4 liter engine. 115° F is a typical summer day temperature. Winter lows are to about 25°. A pretty severe climate (edge of the Mojave Desert). Plan is to go with Michelin Defenders-90,000 mile tread. I drive about 12,000/year.

The tire shop tells me I should replace the TPMS sensor unit if I plan to keep the car for any length of time. Since I am only on my 3rd Caravan, the first being a 1984, I guess I qualify. I trade at 10-13 years. Problem is, the tire shop wants quite a bit for the sensors. The manager tells me if I get them myself, they will install them at no extra cost. I checked the internet Dodge parts dealers, who have substantially lower prices.

The problem is, I don't know how much has to be replaced. The illustrated parts breakdown shows: (First price is list price, second price is internet price)

1. To 1-22-07 Module low tire pressure, .70/37.36
2. From 1-23-07 Transponder, .45/41.16
3. Mounting bracket Left, .20/11.36
4. Mounting bracket Right, .10/7.28

3.Sensor Tire pressure, $72.25/57.80

1. TPMS sensor, .25/57.80
2. Hardware kit, .85/35.08
3. Cap, .70/10.16

Has anyone dealt with the TPMS sensor? How much of this do I really need to replace? Do I need 4 brackets, 4 hardware kits, & caps? What differentiates "Transponder", "Module low tire pressure", and "TMPS Sensor", or are they all the same thing depending on the model?

A different tire shop from the one I usually deal with tells me I only need a rebuild kit that consists of a couple of gaskets. My research tells me that the sensor batteries start going bad at 5 years, and most fail at 7 years. Therefore, replacing them now makes sense.

Your assistance is greatly appreciated. Thanks in advance.