From personal experience, finding somewhere to store lots of books can be far more of a challenge than might be expected. Take a look at lifestyle magazines and you see rooms with dozens or even hundreds of books all arranged in an attractive, artistic fashion - just how much time and money do these people have?
Me, I have a pile of books (well, several piles) and need to put them somewhere out of the way but where I can find individual books when I need them. The obvious solution is to trot along to Argos or Ikea, find the cheapest bookcase that holds the biggest number of books, take it home and screw it together.
Now, this can work pretty well - provided you can find some way to suport your chipboard or MDF creation on each side to stop it developing a middle waist spread under the weight of books. I've also found that the shelves don't carry solid rows of books very well and will eventually sag. Then you end up with the books supporting the case, rather than the other way round.
The solution experience has taught me is to buy a bookcase or bookcases made from solid wood. Ideally they should be a proper carcass or cabinet that has already been fixed or glued together by the manufacturer because these are far stronger than the screw together variety. Wooden shelves have a greater strength than manufactured board and are much less likely to sag under the weight of books.
You can choose all kinds of wood, including oak, acacia or whatever takes your fancy. The only restriction is the budget you have available - and this is why I like Pine Bookcases. Pine is about the cheapest timber you can get, it offers all the strength needed for a bookcase and, because most pine in this country comes from managed forests in Europe rather than the other side of the world, its less damaging to the environment.
Manufacturers are far more inventive with the choice of styles available these days and even offer a choice of finishes including waxed, lacquered and painted. One such manufacturer is PD Global. Their website can be a bit tortuous to navigate but this is a link to their bookcases page. A search for the company on Google should also show some of the retailers where you can buy their bookcases.