Looking to get an idea of what the TPMS replacement cost would be? Are both the front and the back sensors the same part number 21176-0748? I figure a bike shop would be pretty expensive even if I bring them the tires.
First of all, there is no point in trying to save money by taking the wheels to the dealer. After the TPMS modules are replaced the the bike's KiPass ECU must be programmed to recognize the new modules. Doing this requires a KDS3 unit and software. Without this, the bike will not read the new sensors. You'll have the same problem if you just buy the modules from an online Kawasaki parts dealer, there is still the problem of programming. Note, however, that there are some forum members who own a KDS3, so ask around in your area if there is an active COG group where you live/ride.
If your TPMS modules are of the "old" style, then my recommendation is to have someone replace the batteries with new ones. It's easy to do if you are handy with a soldering iron or there are a number of forum members who will do it for you for a reasonable fee. Note: The old-style have a round "nut" below the valve stem vs. a hex "nut" on the new style, so they are easy to tell apart.
If your modules are of the "new" style, they are basically cast-in-stone and replacing the batteries is nearly impossible. If your bike is still under a Kawasaki Warranty, original or extended, the replacement of the modules as well as the programming should be covered at no cost to you. But I'd only do this with the new style of module.
Note that there are some TPMS modules that are advertised to be C14 compatible on auction sites. These may or may not be compatible and you still must get bike programmed to read them. I don't recommend these as you don't really know for sure if they will work until after you buy, install, and pay the dealer to try to do the programming.
Update: Attached is a photo of the new vs. old TPMS modules. Old style is in hand, new style is in the wheel.