If you are on a really tight budged and don't mind the weight the cheap blue tarps would be hard to beat. Maybe buy one and slit the cost.
Another option is a thick plastic drop cloth. Add some ghost tie-outs of the corners and ridgeline.
Whatever your choice I would set this up before you leave. Nothing worse than seeing the rain coming and trying to figureout how to rig something to keep you dry as it starts falling. Speaking from experience on this of course.
Is that too much to ask? Girls with frikkin' lasers on their heads?
The hanger formly known as "hammock engineer".