I agree Chalky - The aprox £10.00 All-nighter / £5.00 Soul Night is now what we are used to.
I feel for some promoters, because the margins can be very tight / and there is absolutely zero 'safety net' for if they have one or two nights with low attendance.
Personally I would be happy to pay £15.00 to a promoter that I trusted to use that money to put on a decent event, not scrimping on kit, DJ fees, door staff fees etc etc etc. Also to have a bit for themselves because promoting can take up a lot of time - More so nowadays because of there being so much competition / which also brings more risk of not so many people through the door.
Entrance fees aren't really a huge percentage of a night out if you travel far / drink / even stay over in hotels which is often the case nowadays, but raising those door prices does seem to be a sticking point, as I said, because it's what we are all used to - Although in reality, I don't think an extra £3.00 would be a 'deal breaker' for the majority of people, and that extra few quid would be welcomed / and well used by any decent promoter.
All the best,
Len