They sent someone to buy dozens of powerbars and extension cords which they chained throughout the room, plugged them into the wall sockets and then freaked out when the room went dark.
AV rental costs are insane. It is a field so ready for a disruption.
AV costs at one hotel I looked at was something like ~$300/day per room. That's ~$1000 extra, on top of the nearly double room rates compared to our current venue. It's just really hard to justify that extra expense just to be in a hotel. Yes, we're within walking distance of downtown, and there's some nice restaurants, but when I've been operating at a loss for 2 years... ;)
At Minecon (a convention for Minecraft) in the Mandalay Bay Las Vegas they were (if I recall the figure correctly) charged $50,000 for wifi for 2 days. It's insane, especially when the wifi was absolutely unusable.
That didn't include bandwidth charges which were included in a different line-item with WiFi which was based on buying blocks of 500 simultaneous users at an equally exorbitant rate.
Catering - people need to eat. 99% of conference venues will not let you bring in random food, or in most cases even professional catering companies, unless they're on an approved list. Snacks/coffee/tea/etc throughout the day cost. Our food cost, including lunch, was north of $20/head. This is surprisingly cheap.
Power - some conference venues charge you for power access. $x/seat or something. We cut down on that this year compared to first year because few people seemed to use it the first years.
Wifi - our conference center has good wifi and it's free. One place I looked at said wifi access was $25/head/day. That's not a typo.
One of my goals was to have an event with non-local speakers. A barcamp is great, but... you end up seeing mostly the same people speak on the same topics. By having people from out of the area (state/region) speak, you'll be guaranteeing most attendees in the region won't have seen/met these speakers before. That costs something. Most of our speakers have been gracious with their time, but I wanted to at least cover some of their expenses in travel. With 20 speakers, and 8-10 with that sort of assistance, that's an additional cost.
I lost > $3k on the first event. ~$2k this time around, and would like to break even this year, or perhaps (gasp) make a small profit. A large profit would allow me to do regional versions of indieconf in different areas, bringing together a mix of local and non-local experts on various freelancing topics. That was the idea 2 years ago, but I can't commit to that until I know I won't keep losing money.
EDIT: oh yeah, insurance. The venue requires an insurance policy. For the minimum coverage, that's another... $600 or so.
EDIT 2: I would have probably broken even this year except for 2 things.
1) speaker dinner. Given the enormous effort many of our speakers put in (and travel) I like to have a low-key speaker dinner that's private for them to unwind. We have a few attendees that pay for a premium ticket to have a few dining hours for some one-on-one with our speakers. As fun as it's been, we may change that event this year.
2) After-party. This year instead of some ritzy club or venue, we had a jazz trio come in and had some catered snacks (veggie trays, etc). No alcohol, but I don't think anyone cared.
Without those two additional things, I think we'd have broken even this year on tickets and sponsorships. I'd rather not eliminate either one, as I think they each add something special for different groups.