Look at these (just to name a few, and not to overlook any...):
Hennessy Hex Tarp
http://hennessyhammock.com/catalog/rainflys/
Warbonnet Tarps
http://warbonnetoutdoors.com/tarps.php
Arrowhead Equipment
http://arrowheadequipment.webs.com/a.../340431?page=1
Jacks-R-Better
http://www.jacksrbetter.com/Products.htm
These should get you started looking at stuff, and will give you more than a dozen to look at in your price range with widely varying sizes.
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