Hello, Nancy!
While we've often purchased matching shirts at our local Disney Store, or at
Disney Store.com, we most recently had
customized, matching shirts created at Disney Store.com. Here's a
link to Disney Store.com's Personalized Gifts page, where you can have a blast creating the exact look that you'd like for your shirts.
Once there, you get to pick the font color / size / location on the shirt, character pic, shirt color and size, as well as the text you'd like printed on the shirts. You'll get to see a virtual rendition of the shirts you're creating, too, so that you're sure you like what you see before you place your order. For an upcoming extended family vacation / special birthday celebration, we had ten personalized shirts made, in various styles and sizes, and they arrived within ten days of my order, exactly as they looked online.
I hope that this helps you find just what you're looking for! Please send me any additional questions you may have as you plan your upcoming vacation to Walt Disney World! I'd love to help!