Cormac, do you think it's worthwhile to join a crossfit gym for a month or two? They're all $175/month in my area. Could they really teach me stuff that I couldn't learn on my own? I don't really give a crap about long endurance even though it's one of the main goals of crossfit. Steady cardio is not really needed for basketball. All I want is more explosive power, flexibilty and maybe anaerobic endurance.
It depends on the gym, to an extent. I hear they are popping up all over and that quality has really nosedived. On the other hand, the good gyms/trainers that were around before it all kicked off are presumably better than ever. I'd look for somewhere established, with a history of keeping their athletes around.
If you find a good gym, you'll learn a ton. Maybe not in a month. A good gym will likely frustrate you in that regard, actually - they'll want to move you along slowly and make sure you have mastered the basics before giving you real weight or testing you with tough WODs. Given your I-want-it-all-and-i-want-it-now mindset...I can see that not working out perhaps. If you go in there to learn, you have to accept that it takes time to learn anything of worth. And even after you've grasped it in principle, you have to learn it in practice, which just takes a lot of reps and a lot of correction.
A good trainer will be able to tell you your weak spots pretty early though, and should be open to discussing how you want to attack them (or ignore them...) rather than shoving their program down your throats. That should be the first thing you look for I think.