The Halloween event would end as soon as tomorrow (November 1 iirc) and the Bremen Reissue Shop at November 10.

The plan in my case is simple. Finish the Halloween first and buy as many ampys as I can. Each one costs 550 pumpkins and there's a dozen for each type so it's quite difficult to buy all of them.

As for Lavender's Reissue Event, 3-4 days are enough to buy everything. Even if the new event comes along, it wouldn't be difficult to dual farm them. The only one with hefty price is Lavender herself with 2000 sealstones. The rest are jiffy.