In all honesty, stay away from 1366 unless you're going big. By which I mean 980x. I wish I would have gotten a Lynnfield i7, and not a Bloomfield. The architecture on the i7 9xx can't keep up with Lynnfield, which means it will be put further in history by 1155 (SandyBridge)
1156, 1155, and 2011 are going to be where it's at.
And, you'll need a bit more than 350USD, lol. Just an i5 (760) is ~200. Gigabyte makes a decent P55 mobo for 120 (though I'd opt to get a board with a little more quality), and 4GB of 1333 runs about 50 dollars.