Sarah,
This is what I used on a joined field and it worked fine:
var renderer = new ClassBreaksRenderer(symbol, "Parcels3.PRICE_SOURCE");
renderer.defaultSymbol = new SimpleFillSymbol().setColor(new Color([255, 255, 255, 0.5]));
renderer.addBreak(0, 1, new SimpleFillSymbol().setColor(new Color([56, 168, 0, 0.5])));
renderer.addBreak(2, 2.99, new SimpleFillSymbol().setColor(new Color([139, 209, 0, 0.5])));
renderer.addBreak(3, 3.99, new SimpleFillSymbol().setColor(new Color([255, 255, 0, 0.5])));
renderer.addBreak(4, 4.99, new SimpleFillSymbol().setColor(new Color([255, 128, 0, 0.5])));
renderer.addBreak(5, Infinity, new SimpleFillSymbol().setColor(new Color([255, 0, 0, 0.5])));
var infoTemplate = new InfoTemplate("${Parcels3.NAME}", "${*}");