Hey Dragon Master! We also like to get as many Gems as possible. There are lots of ways you can earn Gems in Dragon City and not just from purchasing the packs in the shop.
Here are some ways for you: 1) By completing Achievements / Goals 2) Activating the Jewelem's Guardian Tower 3) Watching video ads 4) Completing Offers in Freebies Island
Most of the time you can find them in the temporary islands as well. We also give away Gems on our Facebook FanPage, so make sure you LIKE our page to be notified of when we do this: https://www.facebook.com/DragonCity/