It seems very expensive. What do you get for £320?
Edit: Not a lot it seems reading the site. Some food, somewhere to sleep, a shower, towels and mech support if you need it.
1500 riders @£320= £480,000, plus 100 quid if you want to register a support car, plus you can buy a jersey if you want one.
It looks good value when you realise how the riders do the event, which is riding for as long as they can with as short rest breaks as they can manage
Day and night cease to have much meaning on LEL because most riders only stop for a few hours at a time.
It is a great benefit to them to know all of the controls are open 24 hours a day, and they are guaranteed full service whenever they arrive.
No need to book, so they can make route progress decisions as they go along, stopping at the controls for as long or short time as they like.
Thy can eat and drink as much as they like, and some effort is made to tailor the food towards the needs of cyclists.
There is a bag drop system so the rider can organise access to clean kit.
Self-reliance is at the heart of audax, but the riders know the controls will assist in any reasonable way, and are certainly the place to head for if they get into difficulties, if they are able to head anywhere.
At Barnard Castle we had a few suffering from exhaustion, and two riders of which I am aware who had fallen and were very glad of the basic medical treatment we could offer - "wash the gravel out in the shower and we will slap a bandage on it".
If you make full use of the controls, it is possible to complete the ride without spending any additional money.
Some do that, and I believe most only spend a few pounds on treats - I heard ice creams mentioned quite a few times.
So, as
@jefmcg says, about £64 a day is pretty good for being looked after by hosts who understand your needs as a long distance cyclist.