While back to school shopping with my daughter, we went to look at t-shirts in h&m. To begin with their basic t-shirts are a good price, 2 for $10. While looking through all the different colors I found that some had tags marked buy 2 get one free. Even though that promotion was over the sales lady honored it. $3.33 a t-shirt is a better price then my local thrift store!
If you are looking for some kids t-shirts check and see if they have any shirts with the buy 2 get one free tags on.