Personally, I think to do the event justice, the buyin should be £50+£10 per person. It amazes me that any venue is still prepared to run a two day deepstack event with just £5 per person juice.
To get to the capacities we are talking about, any venue in the UK will need to bring in dealers (which costs a bit more than their inhouse dealers). I"d imagine it"s a hard sell when speaking to venues.
Sorry if that"s slightly off topic, and those are my own opinions, which may well differ from Des and Tom's views.