+1 on what pgibson said. If you're looking for lightweight hiking gear, that's a different end use than around-town, heavy-use gear. Even for someone like me, who's particularly hard on their gear.
Honestly, for the use in sports, you don't need super lightweight or packable. I'd spend ~$40 at the local Army/Navy surplus store and pick up the following: a GI poncho (you'll want the kind with the tan urethane interior; it blocks water better than the regular PU-coated kind when used to sit on and is more durable) and poncho liner. That'll stand up to pretty much anything you can do to it, be waterproof or not depending on conditions expected, and cost you much less than ultralight gear will.
For hiking, I'd go all out and spend on the lightest materials I could afford for the top quilt. And I'd also make sure that my designs were the right size before sewing said material (voice of bitter experience speaking here; you don't want to depend on having a friend just smaller enough than you to sell the quilt to...I got lucky there).
Hope it helps!