I just made a no-sew UQ from my wiggys poncho liner. I also just bought an issue PL to use as a TQ in warm weather. I don't know about the difference in warmth but the Wiggys PL is significantly heavier and stiffer than the issue model.
For an alternative UQ starter material I'm thinking about hacking up my kids' new sleeping bag. I got a Kelty Shooting Star from Target for $20. It's the same price as the PL I bought but I'd guess at least 5 times thicker. The bag is rated for 45F so I figure that's a good estimate or lower for the UQ.