Check out carousell, preloved baby stuff of facebook groups, Craigslist, gumtree and even q10. There are a lot of cheap ones out there.
I'm quite fussy about the info printed on flashcards, so I choose to make my own. You can buy blank cards.
I bought from taobao. Lots of selection, cheap and quality is good. Read reviews before buying them yar
Just buy from carousell or preloved baby goods group on Facebook. I bought my glen doman from carousell
I got it from those popular fair at shopping off one off. Each pack is like less than $5
Thank you everyone for your kind advice! it's been really useful :)