When I was a first timer, we did not take the 6 week class prenatal class. We ended up taking a "How to take care of your newborn" and breastfeeding class. Each were $10 and one night each. I had already read enough about childbirth and felt like I was more worried about what to do once we got the baby home.
For the childbirth, on the top of the self-education we did, I figured...isn't that what I'm paying all these nurses and docs for anyway? To teach me how to breathe or anything else. Plus, all the previous generations of women before me did not necessarily have a class on what to do, so I didn't feel like I needed it. I had an awesome birth experience, btw.
I'm pregnant with our second now and it has not crossed my mind to take one.
Having a baby can be so expensive. I would save your money for buying a very solid car seat instead.