There was some discussion here and on WB about using Mason Line for guy line for tarps and such. The Speer No Tangle guy line I have been using has gone up again in price (.25 per foot, only available in 100' lengths) so I started looking for alternatives. I had checked out my local Ace Hardware but the only line they carry was the twisted nylon Mason Line. This type of line sucks and should be avoided at all costs. After asking on WB, I was told that Home Depot sold woven Mason Line so I stopped by Home Depot and picked up a spool.
The brand was Marshalltown, with 150lb. breaking strength, #18 braided nylon line. It was about $8, including tax, for a spool of 500'. That's less than .02 cent per foot. They had bright yellow and hot pink colors in stock. It holds knots well and doesn't unravel to bad when cut. I tried weighing 10' of the line but it did not even register on my scale. Here's a pic with some orange Speer No Tangle guy line. The Mason Line looks like it's thicker in the pic but that's because it's a flat cord, where the Speer is round.