In my experience, it's a choice between decent Ikea shelves that don't sag after a few years of use and super shitty Walmart furniture that falls apart in about 6 months.

Aside from the price of good quality wooden furniture, it's heavy as hell which is rough when you're a renter and moving every few years. There's also a lot of wooden furniture, old or new, is just as poorly constructed with peeling veneer and failing staples. Not everyone has the time, money, or space to fix that up.

And all that being said, Ikea isn't really that expensive for what it is. Their soft furnishings and decorative items seem overpriced, but their storage products (mostly what I get from them) are pretty decently priced. Yeah I've had my issues with missing parts and shitty customer service, but all in all my experience has been positive enough to keep going back.

I still want to get a couple really nice, high quality items, but I'm not going to break the bank every time I need a bookshelf.