Sitka, Kuiu and First Lite are all similar gear and all are great. Personally, for the price, I prefer First Lite and Kuiu and my set up is a mix of both with an Outdoor research puffy (still looking for reliable lightweight puffy bottoms and I am not willing to pay what Kuiu or First Lite charges... for now).
If you have a limited budget, the best question to ask yourself before pulling the trigger on this type of gear is; what do I need based on my hunts? A mostly treestand/blind hunter will not require the same set up as someone who still hunts or goes on long hikes in the prairies or mountains. For late Nov and early Dec stand and blind sits I normally wear heavy and warm mismatched outfits including old Remington bibs, my grandfather's heavy wool shirt and my high speed Kuiu/First Lite gear. If I'm chasing animals on the prairie or still hunting and won't sit longer than an hour, I wear my high speed and fancy layers of Kuiu and First Lite (what you really need in these situations is a good shell that blocks the wind, over thick layers that will keep you warm for hours).