Alright, so we always have thought that an Endless Gold Mine would be SUPER awesome. But to think that the Endless Copper Mine costs 20,000 gems; how much would an Endless Gold Mine cost? 40,000? 120,000? No one would spend crazy amounts of gems for it.
Here's an idea that, I think, would give BB a bit of MANY player's hard-earned paychecks by encouraging gem spending and get us what we want:
Provide 2, or so, Endless Gold Mines for a reasonable amount of gems (I suggest 20,000), and then provide the upgrades for ONLY gems (I suggest 2,000 gems per level). Oh, and time-limits would apply (2:30, 1 hour, 1 day, 7 day waiting).
We get the Holy Grail and BB gets our money from both the original purchase AND repeat money for the upgrades.
Win-win, right? What say ye?