The reason the packs cost 1200 is because you also get 2 3* trainers as well as 5 world energy flasks.
That brings our cost to 700 for the trainer heroes and 90 tickets. I certainly would believe that the value of a 3* trainer would at least be 300 gem each. It is a 3* after all, not unlike something you would pull from a 300-gem epic summon.
That leaves 90 tickets for 100 gems, which is not too far off of what my suggestion is.
I’d pay that.
EDIT: The “raining loot tickets” deal is 9.99 USD. 1 WE flask (100 gems) plus 1000 gems, plus 100 loot tickets. Again, I posit that 100 tickets for 100 gems makes sense.