That's the one ! I have seen it for a bit less at Costco from time to time.
How long the resin lasts depends on how hard your water is & how you use it.
DO NOT just use a hose & regular nozzle - uses gobs of water (and thus resin). Get one of those cheap electric pressure washers (with low pressure), use the widest spray nozzle and 'sweep' the car from a distance. Be especially careful around stripes, seams, door edges etc. the idea is to wet the car, wash, then gently rinse it away. You can hit the wheels a bit harder than the body, but not too hard.
Supposedly you can just walk away, but my OCD prohibits that & I use a leaf blower to blow most of the water beads (and all the cracks & crevices) off followed by a large MF towel to get every last drop

+ another 'old' MF towel for the door jambs, underhood etc.
Lastly, you can buy replacement cartridges & bulk resin from them, but since like me you are a tightwad, you can replace it yourself & reuse the cartridges indefinitely. Just unscrew them from the unit & let them drain for a while, then unscrew & dump the resin in a HD large trash bag. It is wet & heavy + the beads are VERY slippery so be careful not to spill. Then wash & rinse the cartridges, carefully fill with the bulk resin, put a dab of lithium grease on each of the big O rings & screw it all together.
Bulk resin is available from most commercial window washers stores/websites. BTW you can use this set-up with a bucket of soapy water (I actually use my car soap) & a soft brush on an extension pole to wash you outside house windows !! Those I let air dry & they turn out good with little hassle.
Example of bulk resin:
https://jracenstein.com/resin-di-cubic-foot-new-virgin-resin/