Hopefully this info will help someone out as they are changing the process on how to purchase the two retail exclusives.
Last year, it was pretty much first come first serve. You get in line and wait for the booth to start selling the exclusives. It was a waste of time and not very efficient since they would wait about an hour and a half after the exhibit hall opens to start selling. This year they are handling things a little differently. They will be handing out tickets to the first few hundred people that show up on a first come first serve basis. Once you get a ticket, you are eligible to purchase any combination of up to two retail exclusives, the JEK-14 MINI Stealth Starfighter and/or Microscale Bag end. Only those who have a ticket may purchase the sets. There are a total of 1,000 of each set made, and they will be selling 200 each day including today, preview night. You must purchase your set(s) before 4:00pm else they will be for sale to the general public. The price for each set is $39.99.
On a side note, they are also selling the 21103 Back to the Future Time Machine set as an early bird sale exclusively at the LEGO booth here at San Diego Comic Con. Price is $34.99. The official worldwide release date is expected to be August 1.