O.k. I don't belong to a box but here are my theories as to why:
a) because it's not a come and go as you please like a globo-gym, but a classroom style, they can't fit as many people in their gym in a day so it's a higher price per person to break even
b) insurance is higher since there are no machines and they do oly lifts
c) affiliate fees are high from crossfit HQ
d subpart) some gyms charge more than others. I have one cfit box that would charge me 20-ish a class and the other would charge me 45. Shop around. (funny thing is the one that charges less has sent more people to regionnals and raises 2x the funds for FGB as the one that charges more
See if you can workout a deal where you do the box a service to take some funds off the fee. EXAMPLE- a box three hours from me offered a free membership as long as you cleaned the box. (I would of jumped on that if I could of been closer). If you are an insurance agent, advertiser, lawyer, graphic artists, bookkeeper...on and on and on you could probably offer a service for free for the cost of attending .
Or you can home wod like I do. But you won't see results as quickly and you have to be way way way more diligent about form and programming than the run of the mill crossfitter. (I probably spend an hour a day beyond working out just learning form and programming is your hour of time a day worth 30 bucks?)