Compared a $40 tarp from Walmart to a $90 one from REI, the cheap one actually held up better in the rain last weekend | Camping Gear Reviews - nhfree.com
Got a cheap blue tarp from Home Depot a few years back for like $15. Used it to cover my camping gear during a solid week of Pacific Northwest rain and it never leaked a drop. The expensive name brand ones I've tried always seem to get those little pinprick holes after a few uses. Sometimes the basic stuff just works better.