Jimm 4/21/2013Usually, the cause is contaminated brake fluid. Exchange the brake fluid in the system for new fluid - then bleed the system thoroughly. There may also be a collapsed or restricted flexible brake hose at the caliper. You may have to replace the flexible brake hoses at the calipers (as the hoses are always replaced in pairs) - then drain and bleed the system using the new fluid.
For the replacement parts, try the many on-line parts sources, such as; www.autopartswarehouse.com or www.rockauto.com - to list only two. For example, they (RockAuto) list the flexible brake hydraulic hose from around $7.00 each for your vehicle.