I actually just slung up my DIY suspension last night. I got some tie down straps rated for 400 lbs working 1260 max load. And like old gringo said they are not rated for life support, says so on the tag, but I figure 40 feet of webbing for 10 bucks would at least get me started.
My ridge line I made out of 3/8 wire rope, (that was rated for towing and lifting, 800 lbs working load I believe) I have a couple of steel rings (descender rings?) rated for 800 lbs apiece, found in the same section as the wire rope on either side of my ridge line. I put a figure 8 loop in one end of a strap and use that to wrap around the tree, the other end I run through the rings. Cinches up nice and tight and easy to take down. I hang my hammock from a couple of continous loops of webbing that are hooked to the steel rings. Simple and easy.
One note on tie down straps, the fine print also states that they are considered a "consumable" and will wear over time and need to be replaced after "evidence of excessive wear". By then I plan to have the money to invest in real straps.