By Robin McKinely. The sequel is called the Hero and the Crown and is even better.
Has anyone heard of or read these books? (And if everyone says no I'm going to go hide somewhere and try to figure out what other people read, if they've never heard of anything of mine...)
It's been a long time since I've read either but I remember they were both very good. It starts out as kind of an alternate British occupation of India thing, but it quickly gets out of the British part and up into the mountains. Instead of magic, the rulers of... wherever, inherit this power they describe as Keelar. It's really cool. And it's an intuitive thing, it's not something they can control. And they ride horses and fight with sabers and have long Arabic robes with sashes and live in tents and other really cool stuff.
And the characters are really lovable.The Prequel is even better. The story is about a younger princess who gets injured so she spends her time trying to reinvent a rather vague recipe for a fireproof potion so she can fight dragons. Dragons are small, irritable creatures, more like pests than actual menaces, but she's young and bored so that's what she does... at first. Then the real action starts. I loved this book. I should read it again.
Anyway, I was on the magic forum and something there made me think of Keelar and I was going to mention it and then I realized no one would have any idea what I was talking about so I thought I'd come over here and recommend the books.
My brother says that Amazon is working on getting the price down, but it's the publishers that set the price, not Amazon. I can't see myself paying $10 for an electronic book when I could buy a used copy for $5 and have it in my hands. Something about the paper feel of it is just cool. 
Plus, like you said, the eBook's price is usually prohibitive. 
But I manage. 