Four hrs labor sounds real cheap to me.
I have changed a lot of wheel bearings over the years and 986 are my least favorite. Just always a PITA even with the right tools.
If you MUST do this yourself, make sure you have all the tools you need including a puller and bigazz torque wrench with 6' helper to tighten your hub. Plan to spend 6 hours per wheel. You might get lucky and do it in 4hrs but "stuff happens". I cant wait to write the check to my local indy on this job.
Data point: In 10 years and 100+ track days I only changed 2 wheel bearings. One I did and one my indy did. My brother had to change all 4 on his car over the same period. One of his we did trackside at Auto Club Speedway Fontana, during a Time Trial event.