I wondered that too.
Graphitti wound up selling the Black Lantern Hal Jordan and White Lantern Sinestro on its website after SDCC, and they were limited to 2,000 apiece. The White Lantern Hal Jordan is limited to 3,000, a 50 percent increase. Maybe Graphitti misjudged interest in these figures and is selling them as quickly as possible.
Or maybe it doesn't make sense to hold them until the next convention. They go for twice as much on eBay, so Graphitti might as well take advantage of that and make some money now. After all, toy collectors can be impatient.