The cheapest way to go is with a painter's plastic drop cloth. Then the ubiquitous blue tarp from WalMart (sometimes found in silver or brown). It goes up from there. Right now I am using a recycled nylon rainfly from a tent. It was the right price... free... left at a campsite with a wrecked tent. Stealth camping is camping in places you don't want to be seen. Camo or subdued color tarps are a must for that.
"A knife in a mans hand is as precious as a diamond necklace on a womans neck" Felix Mirando
As the great Andrew Martin once said "One is glad to be of service".