replaced a Macbook Air battery in 20 mins, saved $50
10 - 30 minutes
My battery was failing,
I got the kit from ifixit, it arrived in 1 day, and it took me 20 mins to reaplace the battery
Definitely do it yourself for this repair.
MacBook Air 11" (Mid 2011 to Early 2015) Replacement Battery
T5 Torx Screwdriver
P5 Pentalobe Screwdriver Retina MacBook Pro and Air