I'm a homeowner myself, so I can't really say. I suspect, however, that renting a house would be cheaper.
However, you may also look into the foreclosure home market here. Even though our economy is relatively healthy, it hasn't been unscathed.
Your A+ student daughter should have no problem here, assuming she doesn't find too many distractions.
You didn't say what kind of trouble your son has. If its a learning disability, I can say that several of the school systems around here are aggressively proactive when it comes to kids with things like ADHD.
One of my cousins moved here (to Coppell) from New Orleans after Katrina. He had had a miserable time in the NO school system. He was underperforming and was a couple of years behind in certain subjects.
2 weeks after moving here, he had been tested, found to have ADHD, given a tutor and placed in remedial classes. As of this this writing, he is at least up to grade level in all subjects...and actually helping set the curve in a couple!
Addison isn't Coppell, of course- this town is fairly high-rent & snooty.

But Addison is a nice suburb and should have a pretty good school system. Again, check out the private schools. The ones we have here are excellent, and many of the churches have some kind of private school. Cost, of course, varies- some can be quite pricey, but if you can demonstrate that you've got a kid who has the brains but you're short on cash, several offer reduced tuition and/or outright scholarships.