The costco unit seems to be a $300 unit special purchase. Harbor freight is, well, Harbor freight. If you need one, it is worth comparing features. I have bought some interesting tools at Harbor Freight for superb prices, but also have an amazing array of scrap metal junk purporting to be tools, too. Use your best judgment.
I've used mine several times, works great.
Yes, I've bought a couple of things at HF that turned out to be less than hoped for, but, overall, I've gotten more tools than I could imagine at fabulous prices. Aluminum racing jack, transmission jack, 5 gallon oil drain dolly, wrenches, ratchets, air tools, microfibre towels for the shop, shop towels, tool chests, grommet kits, cotter pin kits, shim kits and the list goes on. The place has been a godsend for a weekender like myself, although, on another board I frequent of professional mechanics, many sing the praises of HF products. Of course, the buyer needs to be discriminating in their purchases. So, for the 5% of things (maybe) that have not worked out, and they take returns with no fuss, I've come out waaaaaaaaaaay ahead. I have two local stores, so I see what I buy.