Yep, those 'biners from Wallyworld will work just fine. I use one on one end of my tarp currently (though not the one with the screwable gate; mine has a spring gate that's less burly) and haven't had trouble in up to ~35 mph winds.
Besides, which would you rather fail first? A $0.50 'biner that can be field-replaced with a knot or a $100+ tarp that requires sewing to repair? Just a thought...