I saved up like 100, then mashed it all one time. In my opinion, buy the tickets with your gems. You win gems back anyway from hitting the goals, so you actually break even. For me though, i played for a while so i have gems to spare. I dont recommend buying gems.
It was rather easy the first time around. This "NEW" event is like the same thing, but right now i can unlock a new outfit. Its not as good as a new hire, with new stories and pictures, but i will at least will grind it for free and see how many more gems i can get.
Since i can log on every hour, i can accumulate tickets, and then spend gems to compensate what i need to win the event. Again, going at it totally free, with some work i can get more gems. Dont spend money on the 10 tickets for 100 gems. You can get ten tickets easy. If your gonna buy, get the middle option, and thats really if your lazy or dont want to waste time. If you log on hourly, you will be able to make 100 in the next 11 days.