The Nike $90 dri-fit t-shirts really hold up but cheapo $25 Nikes are garbage and will start to shred after 6 washing! I now only buy $90-$100 Nike dri-fits! Do not like Nike new contour bottom on t-shirt that is rounded in the back and a little longer then the front. I holding off until Nike goes back to a normal tail.
I second the Ross/Marshalls/TJMax approach. I find most of my tennis shirts/shorts there. You just have to keep an eye out for tennis stuff, and the good tennis stuff. I found a Nike Court Dry Challenger shirt for under $20 bucks at Ross. That shirt retails for 40-50 dollars. Same with the shorts. You just need to keep checking.