Three hours labor is not too rediculous. I only did my lift myself because my buddy has a nice little shop at his house and we just spent the afternoon drinking beer and listening to music while doing the job. It easily took us half a day with both of us working to install the springs, struts, shocks, manual hubs, and wheels (the tires were already mounted to my wheels).
Unless you just want the personal satisfaction of doing the lift yourself, I'd recommend letting the mechanic do the job safely for just three hours of labor.