When the cost of having my outdoor cushions professionally reupholstered was way out of the budget, I came up with a no-sew solution that cost less than $30 and took only an hour or so of time to recover all three cushions .
DIY cushions for patio furniture. Super easy. I didn't have old cushions to cover so I used layers of cheap bed padding foam wrapped in batting. Look here for how to do boxed corners that are not covered well http://craftapple.wordpress.com/2007/09/01/sewing-tip-squarely-boxing-those-corners/