A frequent question is where to buy seal ink and, unfortunately for many, the answer is to buy from an art supply store in China. Since most seal ink sold worldwide is made in mainland China, if you don’t buy it there you will be paying additional shipping and handling fees. And in China you’ll not only get a better price, but more selection. But even in China avoid tourist shops and stationary stores as they will often raise the price astronomically for the unknowing. Buying online is a good alternative although the price will be higher—if you buy your ink from anywhere outside China you will be paying not only the costs of shipping overseas, but also the markup tacked on by the local merchant.
Check the Links page for online sources for Chinese art supplies.