3x5 inch index cards or similar for Hipster PDA

In the States, 3x5 inch index cards are cheap and plentiful. Every office supply store has them because they’ve long been a standard size for small index files. Their scarcity in Taipei is not just a matter of using the metric system-- though of course that’s the most prominent reason. I’m having trouble finding anything similar. I guess offices here just don’t use good old fashion analog index files.

The reason I’m looking for them is to make a Hipster PDA. But everything I find is either too small, too thin, or too square, and often has cute little cartoon puppies or inspirational phrases in funny English.