für or dative?

In Lesson 14.7 (German Cases part 2) there is a sentence

Ich kaufe ein Buch für meinen Bruder - I buy a book for my brother.

I think this is to provide an example of how für takes the accusative.

(Different prepositions take different cases. A bit like Latin!)

Would it also be correct to use the dative, i.e.

Ich kaufe meinem Bruder ein Buch. ?

And if so, which is more likely to be used?

Both are correct, and both are in use. We need to know them both. 

It's much like dative as a replacement for genitive.  

Thanks for that, I thought as much.

I'd still be interested if one is more common, or whether it's a personal thing.

In my experience (admittedly not expert), it's about equal among native speakers. I do think that “für meinen Bruder” is more natural for English speakers and, given that many native speakers use it themselves, there's no good reason not to be comfortable with that.

Hallo Peter--252 und Doughoople!

Thanks for your input Doughoople! I agree, the two versions are both equally common and it's good to know both. 

Grüße,

Julia

Thanks both for your help!