It's still in stock from what I can see. Also, the price has gone up quite a bit since release. So you may want to jump on it now if you don't want to wait for the lighter blue version.
That could be tricky. Maybe people are scalping the 1st one but you may have to wait for a second run. If I were you, I would jump on the lighter blue while it is still around. A3&U appears to have those.
Don't get me wrong, If you can still buy a diaclone black tracks, you can still find a 1st run Sphinx. But wait to see if you can get a reasonable price or for the next run.