Yeah agreed, 2x4's all the way, though to be fair 2x4's are overkill. People underestimate the strength of wood.
Shop bought stands are usually inadequate looking skinny things that don't even look like they're up to the job. But would a shop sell stands that haven't been thoroughly tested, after all they don't want any claims against them. Truth is, even those skinny shop bought stands are strong as hell.
But for DIY stands 2x4's are generally the way to go for many. Enjoy your build.