I looked into this recently, and didn't find much that's oriented towards bushy use. What I found was very heavy and probably aimed more at builders and the like. Waxed 18oz cotton is pretty heavy when you do the numbers. Dry, it works out at around nearly 4kg for a 3x3 tarp, and my experiments with waxing lighter fabrics suggest that the wax adds about 50% to the weight. I also looked at a place in the US (etarp.com), but they were pricey for their lightest offering (treated for mildew and waterproofing, but not waxed), and that was still very heavy. They wanted $168, which I reckon is probably high enough to get hit with VAT and any duty. Also considered the completely untreated 'reenactor' tarp that a German outfit sell on eBay, which is cheap (about £35, I think) but still heavy and has little in the way of attachment points.
In the end, I got one made by bilmo-p5 of this 'ere parish (it just arrived today). After considering some ready waxed fabrics, I went with unwaxed, showerproof burberry cotton (burberry is a type of weave, not a type of check pattern that looks naff), which turns out to be extremely windproof - very difficult to blow through it (unwaxed) when I hold a layer over my mouth (easily good enough to make a windproof smock or the like). It's also very light at about 6oz per square yard - the full 3x3 tarp, with 19 attachment points like a DD, weighs 1.65kg. (My base calculations from a small sample, not accounting for reinforcement patches and webbing loops, came to 1.52kg, so the finished item is right in line with my expectations.) I plan to wax it myself when I get round to ordering the several tins that will be needed, and that will take it up to about 2.5kg, or around 5.5lb. Far better than the heavier options I considered at first.
I had a quick look at the tarp when I got in from work, and it looks like a quality, well made product. I gather Ian (bilmo) doesn't carry stock of this fabric, so I went with 7m instead of 6 (1.5m wide, so 6 for a 3x3). The extra takes care of the reinforcing patches and the surplus means I have matching material should I ever need to do any repairs (which is perfectly feasible with waxed cotton, of course). By the time I've splurged on the tins of wax (about £25 for 8 100g tins), I'm probably looking at close to the pre-VAT price of the one from eTarp, but waxed, lots of loops, and probably less than 1/3rd of the weight (the eTarp guy said shipping weight would be about 20lbs).
I have to say that the service from Ian was excellent - can't fault it. I don't know if that particular fabric is still available, but I dare say an equivalent can be found, and he should be able to supply something made from waxed cotton as well. I would definitely recommend him if you're looking for something that's at all similar to what I was after.
