Have you tried just walking into your local Gamestop (if you're in the US or Canada)? That's how I got mine.
Called the local store up the day after pre-orders started and they surprisingly said they had "plenty" even though their website said otherwise. Apparently they were only doing preorders in person.
This was a month ago and again the day after preorders started, so who knows if they still have some, but probably worth a couple phone calls. I saw a note that GS will have additional stock (more than just the preorders) in person on release day.