…You were looking for a light tarp or tent that was inexpensive but quality. Were you going to see about making one? If not, check out GoLite's "Poncho Tarp." They're having a sale, and for your first purchase, you can get 40% off. That makes an $80 dual purpose item only $48. I picked one up, they're only 7oz. Team that with an inexpensive water-resistant bivy at 6-9 ounces, and you have a pound of less for your shelter. It's also flexible: no rain, nice night, cowboy camp…no rain, buggy jump in the bivy; storming and nasty, you've got a little shelter to shelter your shelter with. :)
Windshirt: I have the Houdini, and can speak to it's beauty. :) Wore it recently on a 5 mile hike in a torrential & gusty downpour (temps in the high 40's/ low 50's), with just a midweight fleece and a capilene 1 baselayer, and I was toasty and for all intents and purposes dry at the end. Residual moisture, but hardly noticeable, and core was bone dry. Keep checking the Gear Swap here. I just picked up a backup windshirt (different style) in my size for $35. Be patient and let the gear come to you in the Gear Swap. Hopefully you can grab it before others can.
I'd look at layering over any one big jacket. Merino, fleece, whatever your flavor. I've found that layering is gold. If it makes you sweat like a hotbox inside, though, you may as well just walk around in a shirt. Going to get soaked anyway.
I picked up a Nano Puff in the Gear Swap for much less that it's retail. I really like it. An effective layering system I've found for the West Coast/Sierras that's worked for me:
Houdini/windshirt (with basic DWR properties)
Nano-Puff
R1 Hoodie
Capilene or merino layer
I hate being cold, so sometimes I have to hold myself from overpacking on the clothes end. My name is Dug, and I'm a recovering clothes-a-holic. :)