There is a uniform shop in PIT. However, it's not in the terminal. The shop has everthing from shirts to flightcases, to Bancroft covers (hats). The shop is about 10 min drive from the terminal and if you call the owner Ray Kearns, he probably will pick you up. Or you could call him at (800) 495-4225 and tell him what you need. He is a really nice guy. I was in a bind a few weeks ago when I left home with only one shirt for a 5 day trip. I went to his shop found a shirt and was surprised he did not take credit cards or his credit card machine was inop. He told me to just take the shirt and pay him with a check when I was back in town. How often does that happen???
Give him a call and he'll fix you up with whatever you need. Also his prices are the same as Cintas.