55​.880 pc

I spend 54.100 for Super pixcoins alone, and then 1​780 pc on miscellaneous items. I got all the Halloween items I wanted this year, and made up for a missed last year! I only obtained 3 halloween items in 2019 - I played more chill.

Edit: and I didn't spend any pc on any auctions or usershop purchases other than what's listed below in the spoiler.

Also, fun fact, I found a total of 37 Black Colocrows and 6 Draooks during this Halloween.
Last year I found 6 Colocrows, and I forgot how many Albino Colocrows - maybe 2-3, but more likely 2.

Edit 2: I had about 48k pc at the start of the event, pets kept bringing me lots of pc after each hoard, and I sold many items on the market and dealer's den during the event. After the event I was left with 28k pc, so factually speaking, I didn't loose that much pc from the sum I started with.
For how much you spend on super pixcoins, you do get a portion of that pc back from each hoard, especially if you send legendary/evolved pets and sellback eggs.

Detailed calculation under spoiler: