My Father in Law has not one, but TWO Priuses that he purchased to save gas. He's got a long commute, and is fairly intelligent, but I nearly couldn't put myself together when hearing the cost of those black holes and the justification for purchasing them.
Does everyone outside the MMM community simply forget about the vehicle cost when saving money on gas? It strikes me as profoundly stupid to plop down $10-15k just to save a grand or 2 per year in gas.
That sounds like a decent deal to me. There are very few things that return ~10-15% ROI. It's likely more than that, since Prius owners pay far less for brake work b/c of regenerative braking and the cars in general are as or more reliable than other yotas, but still... A car that pays itself off via savings sounds like a good thing to me.
Replacing the batteries are a whole different ball park of cost for a prius vs a regular car. Just because the electric batteries have come down in price doesn't mean they are anywhere NEAR as cheap as a regular car battery (especially because regular car batteries are common... I can wheel, deal, and barter for those. And less likely to be damaged in a crash, so it's easy to get one out of a parts car up here).
So I would say the whole supply/demand (scarcity) thing is an issue here.
It depends on where you're located, but individual replacement modules for a Prius run about $40 each in large metro areas, which isn't too bad. My Prius recently threw the usual error codes for pack failure and I ended up replacing a pair of modules (one of them is still good) for $80. The pack itself is also pretty robust. It's located under the rear seat and has 3 brackets holding it down between the rear strut towers, so they don't tend to be damaged unless there's a really really bad crash.
Having said that, as time goes by individual module failures become more common and sooner or later it'll be less time consuming/frustrating to replace all 28 battery modules rather than play whack a mole with individual modules, which runs ~$1000+ for a ~1-2 year old salvage pack. That however, should get someone another decade or two of trouble free driving, at least from the battery pack.