Walmart carries the largest selection of Carter's baby clothes. Target carries them as well. I think that Walmart has the best prices and the best selection. But Carter's also has several outlets located throughout the United states. They have the best deals by far! it is worth driving to your outlet center a few towns away.
Actually you don't have to look too far to find them. JCPenney has a wide selection of high quality Carter's clothing for a good price. Wal-Mart also has a line of Carter's clothing as well that is affordable but still really cute. It has the same high quality as do all Carter's clothing.
The manufacturer Carter itself, sells these brands. I have seen Walmart, Kmart, Baby Gap, Target sell these type of clothing. You can also check online for other retailers that manufacturers Carter baby clothing too.