I'm always on the hunt for sourcing calligraphy supplies that others from outside of the UK recommend. Here's where you'll find some of what you need. If you're looking for something I haven't included, just drop me a line and I'll see what I can do!
Mastering Copperplate Calligraphy by Eleanor Winters
Modern Calligraphy by Molly Suber Thorpe
Learn Modern Calligraphy with a Cup of Tea by Lindsey Bugbee and Simon Rous
*Please note, as an Scribblers and Amazon affiliate, if you click a link here and purchase something from those websites, a small percentage of your purchase is attributed to me. I don't recommend anything I haven't tried, and, where possible, I support local suppliers.
Skillshare (especially Seb Lester and Jackson Alves)