Quite funny - how many players who have saved for a gem pit with free gems do you know? I'm on the same server as you and know none Sure, it's doable, but that's an uber-hardcore achievement, and even in couple years there will be maybe handful of such people on Ares... These players have close-to-zero impact on BB sales
What about:
10. Add achievements based on real money spent on gems
11. Add special gem items (decorations would do) that can only be purchased if you have spent $1000/5000/10000 and more
12. A free 100-unit slow general (with unique animation) for those who have bought everything from the shop
Heck, the paying elite needs some competition too, right?