Mainstays 71″ 5-Shelf Bookcase with Adjustable Shelves, True Black Oak.

I have 4 of these and yes they are not the greatest material, but what do you want for $30-$60? All 4 of mine are 4+ years old, all shelves filled with novels, textbooks, and wildlife encyclopedias (so not light books) and have 0 issues with warping and sagging as several people have mentioned in the reviews. That being said, yes if you have $200 to spare for a bookshelf by all means buy better quality, but if you want a quick “throw it together” cheap option…. can’t beat $30 shelf