That Craftsman unit that Sears sells for $399 is a good unit. I purchased that welder and did ALL the welding on my car with it. Floorpan, firewall, lower cowl, A/C block-off plate, subframe repair, exhaust system, etc).
I never had a problem. I can attest to the durability of this unit....as I tipped over the whole stand and the welder hit the ground HARD, but kept right on going.
Plus it's a gas/gasless welder, and it doesn't weigh too much where you can't just drop it in your trunk and take it with you for those "on the road" repairs....
Highly recommended. But then again...what do I know. Oh yeah, maybe I know a bit. Check out my website below for all my work.