Spinning can be as expensive as you want to make it.
As Mike said, a wooden toy wheel, a dowel and small cup hook and you have a spindle.
Some folks say that you need a wheel if you want to spin a lot of yarn. I disagree. Some folks don't have long blocks of time to sit and spin on a wheel but they can take their spindle & fiber any where and spin a few minutes here and there.
Starting with a raw fleece takes time (and practice) and more time. It is very rewarding, but a time hog. You can get nice fiber for spinning inexpensively from Carol Lee at the The Sheep Shed Studio
I find time to spin, knit, crochet & weave ... then again, I'm semi-retired.
Learning to spin can be frustrating, but don't give up! One day it just 'clicks'. Check out youtube videos of Abby Franquemont (author of Respect the Spindle
Do I think it is worth it? A thousand times YES!!