1 daily summon + 6 tickets to get 3x synergy units (all 50%, so 150% of my own + 50-100% from a friend). Not bad I guess. My shopping list:
vitality apparatus -- 3,500
tickets -- 28,000
atk 15% -- 35,000
megacite -- 15,000
cactuars -- 10,000
quartz -- 3,000
6* mats -- 24,000 ??
sacred crystals -- 3,000 ??
At 200 per run + synergy, I'm looking at around 7 days of farming to buy my whole list, but likely will skip some of the 6* mats and crystals. That's not counting the rare spawn guy who gives a big currency boost. Don't know how big his bonus will be, but that usually cuts 1-2 days off the farming if lucky.
So far my Noctis + Ling have been soloing the event easily (Noctis + Ling + 4 synergy chumps), but paralyze has landed on the final boss each time (dance of death). Not sure what will happen if paralyze ever misses.
Edit: 140'ish energy sunk into farming the ELT boss and not once did paralyze miss from Ling's dance of death.
Edit2: Ok, paralyze missed finally. Boss did some AoE w/ paralyze on his turn that did ~30% damage to the non-carries. Ling cured Noctis, boss still died round two. It's going to be an easy, but boring week.