How long does MCSE cbt usually take?

I don’t really have a job that makes it easy for me to commit to regular classroom based classes, so I am looking into the MCSE cbt classes to see if these might make a better option for me.  Can anyone tell me how long these classes usually take people to complete? And how expensive they are compared to the classroom based instruction? That would help me to figure out which way would be best for me to learn the information I need to know in order to pass the certification exams.  I usually do well with self study type things, so I am leaning toward the cbt.