I just picked up a used/like new Patagonia Micro Puff on eBay for $45. These have 100g Primaloft One. Patagonia isn't currently producing these in a vest. I only had to watch eBay for about 10 days and several came up for $50-$100. Some were the older pullover, half-zip style.
Regarding the Generator recommendation, I have the Rab Generator jacket and it is very nice as I'm sure the vest is as well. Between the Generator vest and the Micro Puff vest, the MP is a relaxed fit and would bet the generator is a more athletic fit.