yesterday, went coyote hunting with one of my friends. it was 36 on out first stand. I was dressed in three layers, a long sleeve heavy tee shirt base layer, a wind proof Sitka vest, and a cabala's light camo jacket. while it was cool, I wasn't cold. then as the hunt warmed up, I shed layers. had it not expected to warm up, I would have added a thermal layer as my base layer and would have been toasty. It doesn't take any bulk or mylar or debris if you use quality gear.
The most expensive thing I was wearing was the Sitka vest. but I know it is 100% effective at blocking wind and does a surprisingly good job of keeping your body heat in. other than I needed it to be in camouflage, a golf windproof vest would probably do a good job as well.