Walmart, in-store or walmart.com: Fair quality, dirt cheap
Veterinary Apparel Company is my favorite. You can get just basics, appropriate for any clinical setting (not just vet offices) very high quality and decent prices.
Walmart really does have a nice selection of affordable scrubs, and they are good quality. Half of my closet is made up of scrubs from Walmart, and I have zero complaints. I would avoid scrubs that are too cheap, because the material tends to be thin and unforgiving, and they tear easily… not to mention that lighter shades can be downright see-through.