It's available in 2-lb. spools, both gas shielded and gasless flux-core. Not cheap, but pretty reasonable. Check Ebay or your local welding supply store. I think it would still be wise to pre-heat, peen, and post-heat a project, plus burying the welded part in sand for an overnight cool-down, but the welding part itself would be a lot simpler with a MIG. As always, practice on some scrap before you tackle the actual project. There are some cast iron TIG rods on Ebay, also.
Jerry
