You get everything with the YesWelder except the tank and gas. They also send you little things like a metal thickness gauge.
Yeah, I went to a place called AlCobra here. You've probably got some places around you. Just ask for Rem Steel (Remnant - left overs from cuts they've already made). That will save you some coin. Also, tell them what you are doing and that you're just starting out and want some stuff to practice with. They should have some good ideas. I don't think there's anything over 3/16" on our Jeeps