$$ = $100/5yrs
Time = An online application. Needed a bunch of previous addresses and employer info. Maybe 30 minutes. Then I waited two months or so for my application to be approved. Then I had to do a face-to-face interview with a CBP officer. They have offices in Cleveland, Cincinnati, and Port Clinton. I went to the one in Port Clinton. Interview is ~15 minutes. Had to take my passport with me to the interview and was fingerprinted.
Paperwork = Just the online application
Totally worth it. And supposedly as long as you don't have any criminal charges within the five years, renewing is as simple as just paying the $100 for another 5yrs. Global Entry includes TSA PreCheck. They do a much more thorough background check apparently for GE.