Groupon is usually a great way to get into the introduction class and test the waters.
What you want to look for is quality coaches. I prefer a gym that has a background in oly lifting, gymnastics and mobility. Just because they have an L1 Trainer certificate doesn't mean they're good coaches.
Also look at the equipment. See if they take care of them. See what equipment they're offering: GHD machine, Rower, Farmer Carry Bars, Assulat Bike, etc
Find out what other programs they're offering with their membership for free or discount: yoga, oly lifting classes, gymnastic classes, massages, diet/nutrition program
Crossfit is expensive. Try to stay within $120-$175. It depends on what they're offering, location, quality coaches and programs.
My current gym coaches sucks when it comes to some of the CF movements, squatting and oly lifting. However they have a good Crossfit program and core/yoga program. They're $120 a month. Unlimited. However there's no oly lifting background at this gym. Although I am experience enough to train myself, it would be helpful to have a coach with that background. I am having to pay extra for a oly coach on a competitor level. But that's by choice. Also, they lack equipment that's beneficial for oly lifting such as blocks.
The problem is they're the only gym on my side of town and it's 2 blocks away from the house
I was at a gym that was charging me $150 but I had everything: equipment, quality oly coach and gymist coach. Along with free classes and massage. And they had all type of free seminars that were offered to better the community. Including social events to get to know the people within the community better.
Ask the members that had been there for years plus. They will be honest with you about the community and the coaches. A lot of these CF coaches are ********. Watch how they encourage or provide the proper attention to the classes and athletes. You'll know right off bat.
Good luck