Those Costco tents aren't bad at all for $50 or so. Compare them to the CHEAPEST backpacking tents at the outdoor stores and prepare to see the cheapest models at $200+. It goes up from there.
My Costco tent might weigh 1/2 pound more than the best ones, and it's not a cool outdoors name brand, but mine only cost me a FRACTION of what the "good" tents cost. Like it matters anyways for the casual camper or the average backpacker. As long as it keeps the wind and rain out, who cares?