It's not possible to give you even a ballpark estimate because we don't know what you did exactly. But, it would be hard to damage the subframe because there are a number of other much more fragile parts under there that you probably bent or broke. Tie rods, control arms, ball joints, sway bars, wheel spindles, the rims, brake lines, and other parts are very easy to bend or break if you hit the curb hard enough. They will bend or break before the subframe does. You need to get this car up on a lift and have a qualified mechanic inspect all of the parts under the front end of the car. If it's making that much racket and appears at a 90-degree angle, something is severely bent or broken, and I would say the car is not safe to drive. Depending on what you bent or broke, repairs could be in the several hundreds of dollars. Right now is the wrong time to worry about looking like a moron. That time would have been right before you hit the curb.