As someone who has “drank the kool-aid” I think the best advice I can give is to pick a reputable box. I lucked out with mine because the first one I went to was so great and filled with extremely knowledgeable coaches and small classes. But some places will have very large classes where it is near impossible for a coach to maintain proper watch over everyone.
Also, as CrossFit becomes more popular and gyms see it as a way to bring in lots of revenue it is important to make sure the gym you are choosing is an actual CrossFit affiliate with experienced coaches. I’ve noticed, especially in the suburbs, that gyms are starting to offer “CrossFit style” classes. Considering the technical movements a CrossFitter performs, I personally feel more comfortable knowing that the programming is coming from someone who understands what they are doing and knows how to pair up skills/strength work with a WOD.
I do agree that in order to get the most out of CrossFit you need to be fully committed. Yes, it’s crazy expensive, but when you do the math you are paying a fraction of the cost of personal training and getting the same results. If I go to class 5 times a week I pay $11 per class.