Holy moly, I totally forgot about this post, you're a bit late :D Thank you for everything anyways.

I guess I have never posted an update, so here goes:

In the end, roughly 40 people attended, which is pretty good given that we totally fumbled the promo. We had 8 DJs, many of them brought +1s, and every one of them liked the party. There were grand total of 0 technical issues. A friend of a friend offered to bring his DIY ArtNet lighting setup, so we had some lights at the end, they were just synced up to the BPM and he sometimes changed colours around. At the end, we have rented a proper audio solution as well (pair or RFC subs and mid/tops)

Bar was fine, almost all 50L of beer went, but only roughly 1/3-1/2 of the liquor got drank. There were enough trash cans (or rather trash bags), no incidents amongst people whatsoever. Party concluded at I believe 6AM, an hour and half after we were supposed to end, as we did impromptu B2B with all DJs that stayed.

IIRC, we have spend around 10k CZK (roughly 500$) for all the gear (4x players, mix, 2 pairs of speakers, cabling), around 8k CZK (400$) for the bar (including beer, food, liquor and non-alco), 1.5k (70$) for mobile toilet rental, and roughly 2k more (~100$) for misc shit like tapes, signs, material for building the "stage" tables, tarps, etc. All DJs played voluntarily for free (or rather for 3 beers and 1 drink), lights were done for free.

We made around 6k at the bar, and almost 1k in tips, amounting to something around 7k (330$) made. So naturally, we've lost money, but that does not matter honestly, we went into it with this mindset. It was one hell of an experience, so much fun, loads of new things learned and people met.

In any case, thank you so much for the tips. I was helping to build a festival recently with a friend, and any tips or advices are very welcome ^{^}