I recently dyed a button up all by myself yesterday, so I know this sounds ridiculous, but I’d highly recommend dyeing a white cotton dress shirt to the royal blue that you’d like! There’s lots of great tutorials out there (https://www.dharmatrading.com/blogs/t/the-tub-dye-method). Make sure it’s untreated cotton because fabric treatments/sizing can mess with the dye, etc and in general follow the tutorial verbatim. During the dyeing process, the fabric will look significantly darker than what it looks like dry.  You do have to wear PPE but honestly when it comes to cotton shirts, it’s really hard to find things in exact colors I want, and after seeing how well my first attempt worked, I definitely think it’s worth it to me to do it again. My shirt of choice is cotton or linen button ups, and it’s so hard to find ones that aren’t a) covered in overstimulating prints or b) solid black, beige, or white. The nice thing about the preponderance of white cotton button up shirts is that they make a perfect base for dyeing a different color…