Most service dog trainers are volunteers. Those who are in paid positions receive an average wage of $10.60 (U.S.) per hour ($21,200 per year). It isn't a good job if income is important, but it can be very rewarding in other ways.
Guide dogs are placed at significantly below fair market value for the amount of work that goes in to them. Part of the difference in what they cost and what the blind person is charged for them comes from charitable donations. Part comes from donations of time. most of a guide dog's training is done by volunteers.
Those that do the finishing training and the instruction of the blind person in how to use the guide dog might make about $10 per hour.
In short, if you are worried about how much money you'll make, working at a guide dog school probably isn't for you. It simply isn't a high paying job.