HF 21 gal. air compressor?

Even if the HF unit is the dreaded direct drive, as long as it has a cast iron cylinder, and it looks like it does, it will be ok. You're not looking for the best and that sure ain't it, but HF will warranty the thing if you drag it with a chain behind a truck. If they offer an extended warranty, I'd get it. If there's any way you can isolate it from where you will be working, do it, because as mentioned they are LOUD. It'll get you by until it either breaks or you can afford something better. Who knows? It may not break.