If you have $100 to spend on a tarp, definitely get one made of 1.1oz/sy silnylon. It will weigh about 1.4 oz/sy after the silicone is applied and will pack smaller than you can probably imagine!

Several venders have variations of these. You would do well to wait until you've gone out a few times with your blue tarp; then you will have a better idea of what fits your needs best.