14 days of training including a complex airplane for $5500? Sounds pretty cheap. Gotta figure at least 20 hours of flight time (that's at least $2500 for complex plane rental), making the instructor's rate around $200/day -- rather low, in my book. PIC would charge almost $9000 for two full weeks of training (and that wouldn't include the airplane), and my personal rate is $350 a day (probably going to $400 soon).
In any event, I see nothing wrong with an intensive CFI course as long as the instructor has a lot of experience training students, is not new to training instructors, and has a well-organized training syllabus. In addition, the trainee must be ready to cut off all home/family/job/business connections for the duration of the training period and fully devote him/herself to the task. Also, for a 2-week course, the trainee should be willing to take one day off halfway through to regenerate his/her brain/body, and that should mean paying at least the instructor's expenses (if not the regular daily rate) for that day off.