Most health insurance companies and health insurance plans do cover the cost of back surgery if the back surgery is deemed medically needed because it's keeping you in severe pain and making you unable to work etc.
Medicare sometimes also covers the cost of back surgery so you'd have to look at your health insurance terms to see what they actually cover.
But if you have to pay out of pocket completely for the back surgery it can cost from $100,000.00 to $170,000.00 for the back surgery.
With health insurance you may have to pay a deductible but it will be much cheaper than paying completely out of pocket for the back surgery.
Only have back surgery if you have no other choice though because sometimes back surgery can make your back pain worse.