The problem with the daily bonus is that it resets after five days. So technically you can only get gems every four and five days. Some one did the math and calculated that it would take five months to save enough gems for Rarity and two years and three months to get Rainbow Dash.
Does Fluttershy cost gems? How much is Rainbow Dash? I bought Rarity, because I just felt like dropping the cash to get her. But if the other two cost gems, I'll start saving up now... Hooo boy, here we go... --- "It's the decisions you make when you have no time to make them that define who you are."