I bought an oxygen tank from the welding supply house. I return it empty and they toss a full on in the truck. It's cheap. Propane is much cheaper than acetylene and works fine.
If you're gonna be cutting half inch you're not going to want a tiny torch.
I don't think I would be buying harbor freight regulators and torch. But don't buy tanks from someone who can't fill them unless you have someone who will swap .

Visit the welding supply house and talk to them.