Reddit mentions of Yasutomo Natural Suzuri Stone 5 1/2 in. x 3 in.

Based off of my own experience... see if you can find a physical shop instead. Ordering online is going to be somewhat iffy. Sets are almost always tourist traps with low-quality brushes and ink, made more to be seen than to be used. I would suggest buying the equipment separately and packaging them up yourself.

So! Actual stuff:

• Paper: Rice paper, full stop. Something like this would work - Japanese and Chinese calligraphy share tools, so it doesn't really matter if you use one or the other. Gridded paper would also be nice.
  
  
• Ink: Get black sumi ink, which should be available at art supply shops as well as online. I recommend the bottled stuff to begin with, because it's just so much less of a hassle than trying to get the appropriate level of thickness if you're grinding an inkstick. If you do decide to get an ink stick, be sure to get an ink stone as well. I prefer the rectangular ones, but that's personal preference. You add a little water on the deep end, then dip the end of your inkstick in the water and grind on the flat portion at the top until the ink is as thick as you want.
  
  
• Brush: I'd say a medium sized wolf or goat hair brush, like this one.
  
  
• Other nice things: something like this practice book might be nice. Look for water-based practice sheets - the idea is you write over it in water, let it dry, and then you can reuse it. From my brief look at the preview, this book looks decent and also has good reviews. I like its stroke-by-stroke breakdown with examples.
  
  One thing's for sure - if your boyfriend isn't already learning the language, it will kick his ass, because the writing system is just so different. If he's not learning the language, he will also be limited to whatever words come in the instruction book, because it's not like in alphabets where if you know all 26/52 symbols you can write what you want. Each character is unique, and though there's a standard stroke order, you have to just be able to recognise the character in order to write it.
  
  Learning Chinese calligraphy from written sources is going to be hard. If at all possible, see if your local area offers Chinese calligraphy classes for beginners. It really, really helps to have a teacher who can correct your brushwork. A lot of the expressiveness and beauty of Chinese calligraphy IMO comes from understanding what it is that you're writing, and how it should look proportionally, and these things are hard to understand just by reading.