As much as I would love to save a few bucks, quality does matter to me... that being said, quality does not have to = $
Clothing of choice now are adidas clima tees- picked up a bunch for around $15 on sale. Shirts are light, thin, soft, moisture wicking, and fit well (not baggy) with sleeves that are not too long. Solid colors + no collar means I can use them for any sport... bball, working out, base-layer for skiing, etc.
Cotton tshirts are probably the worst option of all, esp in the heat.