I just bought these and think they are really cool.

https://www.amazon.com/Chinese-Flash-Cards-Intermediate-Downloadable-ebook/dp/B00PJ2JTLU/ref=sr_1_6?ie=UTF8&qid=1531408213&sr=8-6&keywords=tuttle+flash+cards+chinese

(you can use the amazon 'see inside' to check out what they're like)

And they're on ebay for about $15 and with alternative amazon sellers.