A vote for quilts here too. Yet a quilt can be made from a portion of any comforter-down or synthetic that covers you effectively with a suitable pad under you. As temperatures drop you add clothes and VBL and finally put this whole package inside a light weight breathable bivy to retain more heat as needed. Not the prettiest, lightest or least bulky end result but very effective.
After using your inexpensive creation you can then decide if you want to move up the financial and performance scale to Nunatak, Jack'sRBetter or a DIY with better warmer and lighter materials.
Have fun with your experiment!