I have recently bought some new shirts from dawah wear @ the ISNA Convention. Hands down they have the highest quality of  t-shirts i have ever seen. I own two of there shirts for several years and they have not shown any wear or tear.
Check them out @ http://www.dawahwear.com

Our goal is to become the first clothing company aimed at presenting distinctive urban styles with unique logos and designs in Muslim wear, far away from the clichés which never represent the traditional and highly moral values of our beliefs.