The biggest flaw I find with your plan, and it's kind of glaring, is cheap barrel. If your barrel sucks, and I mean bad, how are you going to learn how to shoot? If it's a 4 moa barrel, when will you know your improving? Also, a good trigger. Master shooting techniques with a crappy one and yes, you'll be way better with a good one, but it can also help you get better, right off the bat.
My advice, get a complete rifle, I suggest Armalite, they are a great deal. Then decide what you want to change, or just rebuild what you have.