First, welcome to THR.
I picked up a slightly used, and slighly modified (upgraded sights, extended thumb safety, commander style hammer) Springfield GI for right at $400 a few months ago, and I've really enjoyed it. The SA guns are built pretty stout, and used as a base for customization by many top 1911 gunsmiths including Ted Yost, and I believe Jim Garthwaite as well.
Closer to $300 I'd look at the RIA. Their US rep, Ivan, posts here and at the 1911 forums under user name ArmscorBA, and has been very helpful to folks in the threads I've read about RIA/Armscor pistols. I think that kind of customer service goes a long way to adding value to a product. There are many good reviews of the RIAs here and on the 1911 forums.
Going back to the $400 price range you might look at Taurus' new line of 1911s as well. Take a look thru the threads here in the Autoloaders sub forum. There have been several on Taurus PT 1911 in past few weeks, and the reviews are good.