I'm currently working with a physical therapist because I herniated a lumbar disc about 7 weeks ago. I asked her about back supports.
She said they can help by reminding one to maintain good posture, particularly while lifting. That's why weight lifters and Home Depot employees wear them.
I have one from Harbor Freight that was under $10.. Seems well made. Haven't used it yet. Here's a link:http://www.harborfreight.com/lumbar-support-belt-medium-94103.html