If you haven't been into Target lately, and you have kids, go!
They have the $25 soft shell jackets back this year (which are nicer this year!), and they have an extensive line of Champion tops/shorts/pants, better than usual. They also have a line of hoodies and thermal layer jackets designed for the outdoors. The jacket is PERFECT for hiking, it is thinner than fleece but warmer. $20 for it.
In the boy's section, sizes 6-16.
Also, Walmart has mock turtleneck Champion long sleeved tops for outdoors in stock.
As usual, the tops at both places are well under $10 each.

