Was at Lowe's yesterday just walking around, and I found a cheaper alternative to climbing rated carabiners. (Don't know if this has been posted yet.) Anyway, back in the hardware section, by the ropes and chains, there are Quick Link chain links. These are designed to link chain together. The listed Maximum Breaking Strengths vary depending on the size, but they are all fully locking, steel links. (The highest breaking strength I found was 3600lbs. I know they don't compare to the 31Kn MBS's of climbing carabiners, but for hammock suspensions, 3600 lbs will support most people that I know . The cost varies by size, but the largest one I found was only $3. They are marginally heavier than carabiners, but for 1/3 the cost, can't really go wrong.