Do you have a Sears/Land's End in your area? Land's End is known for their quality. Their t-shirts are 20.00 but if you buy 3, you get 15.00 off which makes them 15.00/shirt. They have several colors. If you need to order online, you can usually search for a free shipping code to enter off a site called retailmenot.com.
For even cheaper prices and excellent quality, go to LLBean.com and check out the women's SALE section, you can get a t-shirt for $10-$15. I've had a few for years and they still look great.