I wasn't bashing DIY, I was just saying that IMO to build it for $600 you would be cutting some serious corners. I am all for DIY, IF the person building it has any idea what he is doing. As you already said a lot of the time they have no idea what they are doing which at best creates a poorly functioning gun, at worse a potentially dangerous one. DIY is not for everybody. I personally think that anybody who buys a pre-built computer is an idiot. However, I also realize most people don't know how to build their own. Given the purchaser in question I don't think DIY is a viable option. I could be wrong (I'm not trying to be rude), but so far I haven't seen any indication of that.
Also keep in mind that if he is truly piece parting it, he will need some basic armorers tools which bump up the budget.
Once again, under $1,000 isn't so hard, but under $800 is a different story.
look at stag arms, Olympic arms (many under $800), bushmaster.
I disagree on Oly. Yes they have cheap AR's but in my opinion (and that of other AR owners I know) they are POS's. I almost got one but everybody I know tried to talk me out of it. Then I shot a friends brand new Oly and it had more problems than any other AR I have seen. I decided to get the Tac Master instead. I don't regret that in the slightest.
Also, I have stated every time "out the door". Tax/shipping, etc, pushes most the RRA's, Stag's, etc over the $1k mark.