I think you’re only options are contacting Doc himself and see if he possibly has what you’re looking for or finding used parts someone might be willing to part with. What exact parts are you looking for?
Like Fullbore mentioned contact Doc himself. You can email him at [email protected], or [email protected]. I would try the stratanet email address first or call him direct at 435-722-2520.
Harley's got the right idea, imho. Plus, you would presumably have a stock, trigger, and misc parts that you would have to source otherwise.
I'm in the process of building a .410 on a g-series action. I bought the rifle at a good price, and I'm going to sell the .504 ss barrel after my build is complete. Still expensive, but i can't imagine buying every part piece by piece.