If you have to ask, I'd say no. This is strictly speaking form a financial standpoint (I'm from the Dave Ramsey school of finance too!).
I have also been considering Crossfit so am also interested to hear what people have to say who have done it.
I can easily afford it, but want to see what I can achieve on my own first. If my fitness and health continue to improve, I'll likely consider it to go to the "next level-" for many, working out with a team/ coach will squeeze out that extra effort.