I made an 8x10 silnylon tarp, and it's up to around 26 oz for everything, including mesh stuff sack. I think it weighed around 18 oz before seam sealing with just 8 grosgrain tieouts (2 with grommets for pole tips). To give you some ideas for reducing weight, here's what adds to its weight:
- Way too much silicone seam sealer (forgot that stuff weighs something when applying it)
- Replaced the grosgrain tieouts with nylon webbing ones, and add a few more every year
- 8 10' long guylines (orange "no-tangle cord" from Speer Hammocks = sheathed Spectra pulse line)
- 35' nylon paracord for use as a ridgeline when tied to 2 trees
- 6 small Titanium stakes: I use sticks, logs, trees, or cut my own stakes from dead wood if I need something which anchors better
- Groundsheet is 42" x 84" plastic cut from a patio door insulation kit ($3). This appears to be polycro, and weighs 1.5 oz (if I remember right).
I'm going to have to get a tent this year though. I enjoy sleeping under my tarp (or just in the open) in bugless weather, but blowing snow and crawling bugs are difficult to keep away. Ticks are a significant health hazard. And, sometimes I enjoy sleeping out too much, and find it hard to fall asleep with all of the interesting distractions when out in the open--interesting night sounds I want to search for the source of, stars, sattellites, meteors, deer, the dwindling fire, and not to mention, UFO's and night-hiking sasquatches!

The distractions don't affect my sleep after a night or two (except for the sasquatches), but most of my trips are only a night or two long. Also, my oldest kid (age 6) will be joining me this year, and I'm not comfortable with them sleeping in anything but a tent, due mainly to sleepwalking concerns. (I'm a light sleeper and always wake to the sound of a tent zipper.)
Since I want one tent which will do it all, I'm going to get a Tarptent Scarp 2 with both inner tents--mesh for warmer nights, and solid fabric for winter and cooler nights. It weighs 3 1/4 pounds, but I don't mind the extra 2 pounds for a bug-free or snow-free good night's sleep, even if I'm alone. One reason is that 2 pounds is less than 1% of my body weight.

The double walls will be nice for avoiding condensation issues in very damp weather too.