2 yards = 6' exactly, then seam allowances brings that down some. It would be quite short for most people. Remember, it has to rise up from your feet then up to your chin at least, so just your height may end up short. Ask them if they will allow partial yardage, I'd get 2 1/3 yards if I was planning it down to zero scrap. I got 2.5 yards from thru-hiker and ended up cutting off a foot. Put a sheet over you how you want it, then measure that, and add 2" for seams.
here's some more sources.
2.5 and 5oz climashield and pertex quantum and other lightweight shell/liner fabrics. I used their M90T/P-Quantum kit for my quilt, was nice to buy a bundle and save a few bucks.
Quest was awesome to deal with, let me adjust my order after finalizing. I'd ordered a silly 1" of elastic not 1yd and they emailed to verify I was in fact a bonehead! adjusted order received 2 days after placing. Quest is the best source for silnylon 2nds I've found, and a great selection of remnants for random projects.
http://www.titaniumgoat.com/Fabric.html nobul1 and nobul2, never used but very light fabric.
I believe the 8mm was recommended in the thread I bookmarked that from, they will send swatches, it can't be 8mm thick, that's 8 dimes thick.
2, 3, & 6 oz climasheild, I've never used these guys.
I think I ordered mesh and zippers from these guys a while ago. They have a good random selection and a couple of guides.
Down (ordered 1lb of 900fp - was satisfied, posting for completeness in list)
You asked what I'd order, this is just my preference: 2 1/3 or 2.5 yards of:
Pertex Quantum from thru-hiker, or Nobul1 from tigoat. (I love quantum but the .67oz finished weight of nobul1 can't be beat)
thinnest climasheild apex, looks like outdoor wilderness fabrics
8mm silk in 60" width
You could combine your thru-hike order to get the shell and insulation and save one shipping cost (I believe they charge flat 9.95).
You'd be very rough estimate 10oz and $100. Keep us updated, this exact project is third on my list! but might get moved up to be ready for July/August trips.