As Nintendesert not-so-subtly pointed out, if you are male, you should be using whey isolate and not soy, and should be limiting your consumption of soy milk. You can end up with lots of side effects over time with excessive soy consumption.
The Gold Standard stuff mentioned above is decent, and GNC usually has it on sale every couple of months. Last time I bought some, it was half price for any size container. The EAS stuff is pretty decent, and you're not going to find a much better price than Wal-Mart. Sam's Club sells 5-pound bags of the EAS whey powders for around $25 if I remember correctly. They don't sell those large containers at Wal-Mart though, unfortunately.