It is very doable to build a welded frame stress relieved, and machined where needed for the Hobby market the price is not much difference than an extrusion built machine, and a machine that you won't have to build again, if the builder is setup to do it and does not over charge for made in the USA, which most do, that is why I'm looking at some smaller machine builds lets see how it turns out before the naysayers get going, I will be aiming at a price point and still be a quality built machine, when you can buy in large quantities Rails and Ballscrews Etc you can get a good price break, prototype builds are always expensive but a good starting point to know if you can then build for less in building large quantities
A snip of about a weeks supply of Rails and Ballscrew THK high quality