Like Boris said, Enkeis and Fn01s are good, cheap, lightweight wheels. And they look a lot better than any stock supra wheels.
But you also might not be losing much/any unspring weight depending on wheel and tire size. You can lose 4lbs with a wheel, but gain it all back with the tire. So you might break even, you might lose a little, you might gain a little.
But a lighter wheel is a step in the right direction, just don't expect a 10" wide wheel with a 275 on it to weight a lot less than a sawblade with a 225 on it.
Almost forgot to say something. Even though you won't be losing unsprung weight, you will be gaining more available traction and have better overall grip with a wider tire/wheel package. So a little unsprung weight gain is acceptable for the overall increase in grip.
Tim