Most of the categories in iBooks have free books on the right, retail books on the left.
That's how I flipped through several categories, adding free books to my mother's accessibility-friendly iPad.
Except for Classics.That category is all pay. So when I picked an interesting title on the right I bought "The Best of Oscar Wilde" for $5.
The sunk cost principle says I should give it no particular attention, but the serendipity principle says I should move it up my reading list.