Remember, it's cheaper in the long run to pay once for a good tarp than to buy multiple cheap tarps.
And AS is correct. This is your shelter. How many times have you seen cheap tents in a campsite with multiple tarps draped over the top. I have never had to do this because I've just saved a little longer for a quality piece of gear. But that's just my opinion.
"We don't stop hiking because we grow old,
we grow old because we stop hiking."
-- Finis Mitchell,