try checking out tinny's hast hooch design at www.minibulldesign.com its pretty much as cheap as you could go for a tarp. ive used it 3 times once when it was real rainy out. it worked great if you find a good spot. One issue is that it doesnt have a floor so i just brought my footprint from my REI ARETE and propped the edges up with some sticks so i didnt get my sleeping bag wet. It gets the job done, a little on the bulky side though..... but for 15 bucks total its defnitly worth giving a try.
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Modern civilized man, sated with artificialities and luxury, were wont, when he returns to the primeval mountains, to find among their caves his prehistoric brother, alive and unchanged. -Guido Rey