I sold all my old Polly Pockets circa 2010. I got about £10 per set which was more than I expected at the time, but I do slightly regret not waiting until now to take advantage of kawaii instagram trendhoppers. I never would've predicted Polly Pocket would experience such a random surge in popularity.
In a similar vein, I recently got these two Tokyo Disneysea playsets off Yahoo Jp and they're pretty cute:
https://www.youtube.com/watch?v=d5CZsRaw740