I just got a CORE-15 Scout; pretty much fits the description you mention. It was $630 out the door, brand new. Is it loaded with frills and attachements? Nope. But it is a solid performer that comes from an up-and-coming OEM that now makes it's own barrels, and uses quality forgings or billet receivers, depending upon model.
I also have a DPMS that I recently got. I was considering buying yet another but then came across the CORE for less money.
These type rifles may not be your go-to gun when the SHTF (stuff hits the fan), but they most certainly will perform adequately for plinking and general service. And frankly, the build quality seems good enough that I would be willing to bet the farm on it. I see zero reason why it would fail in terms of reliablility.
I will also note that the CORE-15 brand recently had their top-tier "HARD CORE" rifle reviewed in G&A mag. In that article the author mentioned that he witnessed the factory armorer/gunsmith walk over to a production package-ready rack and choose two examples of the least expensive model at random and then shoot them on a bench rest. Both rifles printed 5-shot groups under 1 MOA! This from their economy rifle offering; the very one I just bought.
While possible to build one for less money, it also takes effort and time. For $630, I got a fully functional AR that has potential for excellent accuracy, and it comes with a life-time transferrable warranty! Even if I wear out the barrel at some point in the future, they are easily replaced. Trigger groups are easily exchanged, should that be a desire. The whole point of these ARs is the modularity of the build.
Buy a cheap one and enjoy it. At some point, if you want to "upgrade" a component, it can be easily and cheaply done. But don't be surprised if the "cheap" gun is much better than you ever imagined.
