+1 on the Wespur clearance section of rope, or TreeStuff (my preference for almost anything i need). Sponsors on this site, click around and you'll find what you want
3 strand is usually the longest lasting in natural crotching. Cheap to boot.
16 strand lines wear well too, for light loads.
But, last time I checked WESSPUR they had 20% off their ½" Samson stable braid.