I'll have to agree to disagree with the other reviews here.
Spirit Airlines is obviously a budget airline with budget options.
The price quoted are usually the bare bone flights (which their website states).
Therefore if you want to bring anything more than a personal item, you'll pay extra for it.
And if you're going to buy the "extras" it will basically cost you about the same as the other airlines.
I for one am glad this airline is around to offer this flexibility.
Ultimately, Spirit got me to my destination pretty much on time and safely. And that's what I expected. I would recommend this for short trips and traveling with a small backpack/personal item.
Do your due diligence and read what's on their website and there will be no surprises.