I was in the same boat a while back and did a lot of research.
I came up with 3 finalists:
North face diad, $200, discontinued and very hard to find.
Outdoor Research Helium, $140, ($120 on amazon) made from Pertex..so I'm a bit skeptical since I haven't tried it yet.
Marmot Nano, goretex paclite, $250 ($170 on o2gearShop.com). This is what I ended up purchasing. I love it! Reminds me of a lighter version of the Arcteryx alpha SL.
Downside though is no pit zips. Medium weighs in right at 8oz on my scale.