Growing up, my mom always bought the cheapest dish soap available. Back in those days, the cheap stuff was good. It wasn't watered down and it washed the dishes pretty good.
When I got my own place, I would go for smell. Then, I got all into "green" products. Recently though, I received an Influenster box with three bottles of Palmolive Fresh Infusions. Three bottles is way too much since between Daniel and I, we don't really have that many dishes to wash.
Anyway, I took a bottle to my sister's during Thanksgiving break and we were all in love with the smell. Plus, it foamed up and washed the dishes pretty well. It's readily available at my usual Target and Wal-Mart.