You don't have to go to a crossfit gym to do a crossfit workout. My friend and I do it in our dorm rooms at college. You just need to know what you have to do and do it by yourself. If the time comes that you want to go to a crossfit gym, by all means, do it.
I play rugby so I do it because it has made me immensely stronger and better with the ball. If you don't have good mental toughness or you're not in very good shape, I would not recommend these workouts.
Crossfit has many issues:
1. It is not periodized and has no structured progression. The exercises are seemingly issued at random and have no natural progression. How can you really track your progress?
2. It is not specific. Crossfit issues general-purpose exercises designed to train you at random. While you may be fitter, it is not the ideal solution for someone looking to train for improvement in a specific area.
3. It is dangerous. A beginner cannot suddenly start doing olympic powerlifts and handstand pushups. A novice to intermediate Crossfitter probably can't do tabata olympic powerlifts (something that is in and of itself contradictory) until failure, then go for a 5 mile run the next day. The leg muscles will be fatigued and the legs will be more injury prome.
4. IT IS DANGEROUS. On top of that, the typical mantra in Crossfit is to do as much as possible. The Crossfit mentality is that 20 bad squats in which you move a grand total of 4-5 inches is superior to 5 good squats where you go through the full range of motion with correct form. Repetitive use of poor form is a recipe for chronic injury.
5. It is not for beginners. You can seriously hurt yourself doing some of the stuff Crossfit asks you to do, especially if you're not well-versed in the movements and lifts you're asked to do.
With that being said, it more closely resembles an extreme sport than it does a real fitness program. I don't fault anyone who wishes to do Crossfit, but it should be noted that Crossfit is more for those who are already very fit and looking to challenge themselves than it is for those who are looking for a starting point. If you are looking to train for a purpose, you're better off building a program better tailored to that purpose... unless of course your purpose is to be really good at Crossfit.
Since I'm recovering from injury myself, my routine is pretty basic. I do VMO bodyweight squats with some basic upper body lifts, and spend time on the bike. I'll do this 2-3 times a week. 1-2 times a week I'll swim some laps. I only play hockey once a week. One day a week I'll do a maintenance day where I wear the knee brace to the gym and do the heavier lifts like real squats (well, box squats) and deadlifts plus some abdominal work.