I was told that they are currently backordered everywhere. Not sure about the facts on that but let me know how it goes if you do decide to order them.
Did Throwdown tell you that? That sounds like something they would say in attempt to keep someone's business.
My 2 cents about camber kits: if you aren't going the inexpensive route (I.e. J-Power/Advance a Depot) you might as well go with SPC. If I'm not mistaken SPC offers a lifetime warranty, so it's worth the extra ~$100 when compared to Truhart, or Megan (which is pretty much the same price if memory serves me right).
For what it's worth, I bought the J-Power kit about 9 months ago and haven't had an issue yet. My buddy, who did the alignment for me after I installed my Street Advances and camber kit, told me to check the arms after a couple hundred miles. He said sometimes the locking nuts on the arms will vibrate themselves loose on the lower end kits. After 5,000 miles mine are still toight like a toiger and the bushings are a-okay as well.