The first thing I would do (and something I wish I would have done) is explore alternatives to the Apple-only stuff before investing a lot of money. Specifically for buying music and books. For example, you can buy music from iTunes, but it has DRM it's impossible to use many of those purchases on other devices without breaking the DRM (like if you would ever switch to a non-apple tablet or phone). Alternatively you can buy music from other sources (such as Google and Amazon) and be able to play them on Apple devices and pretty much everything else. Very handy if you would ever switch platforms or just happen to have a variety of devices/platforms in your house.
Same for books. You can buy books using iBooks, but then can only read them on Apple devices. Or you can use the Kindle Apps and it works on everything (I can read a book on my iPad, then switch to my Android phone, then to my PC then to my actual Kindle and it all syncs up to where I left off regardless of the device). Of course there are some iBooks-only stuff, but I wouldn't buy anything from there I can get from other sources.
Just some friendly advice and lessons I've learned. I try not to wall myself in if there's alternatives, because my household uses a combination of devices (iPad, Android phones, Windows PCs, Kindle readers, etc). Even if I was an all-Apple household, I'd still go with something a bit more future proof and versatile when it comes to purchases of things like that.
Hope that helps.