If you're just worried about prices, 9th June.
But there are some incentives (club shop voucher, scarf, pin badge) for ordering late March/ early April.
Block 15, no contest.
But as others have pointed out, everyone should hold out. At least make a point of not buying them until as late as possible.
9th June is the latest for early bird prices.
Yes, my thoughts is that the PR men are in overdrive to counteract all the goings on this season.
Being the cynic that I am, iIt reads as one big guilt trip because they know sales won't be so good for 12/13.
Page 25 for instance;
http://www.bdodarts.com/1687/08-03-2012/BDO_BRITISH_CLASSIC_AND_EDO_ENGLAND_MASTERS_AT_RICOH_ARENA_COVENTRY
Not the Premier League (what happened to that anyway) but it's still darts, and free entry as well.