cheap tarp weight

I don’t know about Home Depot, but REI sells super-cheap tarps with grommetted corners for tie-outs. This 8 x 6 number I own myself, and it’s fine. It’s noisy in the wind, and the grommets will start to pull out in strong (I’m guessing 20+ mph winds), but it weighs 13 oz and costs $3.50. I used it as a ground cloth. Tied up the corners to avoid creepy crawling from joining me, but should work and a a-frame tarp as well. Even if you have to have it shipped, could shipping + tax add up to more than another $10? They have an 8 x 10 if you want something a little bigger.

I don't have it here to recheck, but I recall the cheap poly tarp I got from Ocean State Job Lot was about 1.5 lb for 8'x10'.

I wouldn't recommend one for a shelter since the grommets get pulled out easily in high winds. I used one a few times before the grommet was ripped out. Tied to another grommet and pulled that one out as well. Look for a tarp with sewn in loops instead of grommets, much stronger. Guide Gear sells a 12×12 nylon tarp that has sewn in loops for 30$. Its more expensive but less likely to fail on you when you need it most.