It's presenting itself as a "conference for Harry Potter fans and academics" at a university site. There are going to be serious academic talks - from such luminaries as the author of "The Wisdom of Harry Potter" (the what???) - combined with a "trial of Severus Snape", a Quidditch game (yeah?), gnome tossing, feast, etc.
The price for this educational extravaganza? Two hunded quid for a residential membership (two nights), £235 if you actually want a room with a loo and shower, and a whopping £160 for non-residential membership. All of this in the University of Reading, a site best known for repeated car crimes and muggings, and not very palatial when I was last there - though I should admit bias, the ony time I've had a motorbike stolen was on that campus.
Meanwhile I've paid rather less for membership of the World Science Fiction Convention in Glasgow a couple of weeks later, including membership in the con and five night's accommodation on a nearby university site, and the university games con I'm attending a week earlier is about half the price. If this was a genuine academic conference the price wouldn't be unreasonable, but it looks like a fan con with academic pretensions, and that's a very different thing.
Anyway, their site is at http://www.accio.org.uk - judge for yourself. I won't be going.