Nice, and extreamly accurate, analogy of what it costs for an app to be developed.
"I want something that works well on one platform" = 2007 BMW 335i = $20-25K.
You want something solid that’ll work web/ mobile web / iOS / Android. Just one of those. It doesn’t need to be the most beautiful thing in the world, but you need it to be solid through one medium. It’s realistic to pay 20K+ for something like this.
I hate pricing up app development work, tho so far, I've been pretty good at it (within 10% for a 2 month project). I usually go for fixed cost, as thats what most clients require, but with that, there has to be some give and take on both sides, especially if there isn't a tightly defined vision up front. I suspect I've been lucky with the people I've worked with.
I think Vlads numbers are about spot on, too. I think I'd be pricing the Q7 at 30-75, not 50-75, but close enough.