The answer is that it depends on the individual player. Source books are excellent for reference materials, and the campaign books can be replayed and tweaked endlessly. All the books have valuable information and feature beautiful artwork in them. However, an individual book can average a cost of around $30-$60 or more so they are expensive. As well, a lot of the information about game mechanics that they have can be found online easily and for free. And it is possible to find a lot of these books either at resell shops or at your public or university library. So, again, it is up to the player. It's always beneficial to figure out what method works best for you!
The UM Library system actually has quite a few of these books available for check out!
The Wild Beyond the Witchlight: a Feywild Adventure by 
