GIFT: Harmonica! ONE OR MORE? For beginners.
 

Hey guys!
I’m planing to buy a harmonica for my boyfriend this x-mas, and thus-far I figured one should at least buy the first harmonica with the key of C. However, some places I read you should buy a whole set, and others say buying one at the time is just fine.
I’m not totally positive my boyfriend will dedicate an enormous amount of time to harmonicas, but he said he’d like to learn (even if I think he might be a little tone-deaf), so I figured I’d surprise him!

SO MY QUESTION IS: What should I do? Buy one? Buy two? Buy seven? Can I buy a harmonica with the key of A, or does it has to be C? If I’d buy one with an A, would it be a problem for him to learn how to play it?
Any tips will be greatly appreciated. I’m planing to buy one over eBay, so links and such would be awesome (but needs to ship to Europe)!