From what I understand, they're no longer hard to find as stores are getting new shipments every week. I sold mine a few weeks ago on eBay once I decided I didn't have time to play anymore, and I could barely recoup how much I paid for it at launch.
At my Target, we seem to be getting a few every week or every other week. They still do disappear from my store though within the day they arrive. It's not as big a deal, but I still think you just have to call ahead or get lucky and pick the right day when going out to a store like Target or Walmart to pick one up.
Oh, and get Kameo. I'm having insanely amounts of fun with this game. It's not really original, but it is really just easy enough to pick up and difficult enough to not run through in 5 hours.
Is anyone else still playing this? I got a DS Lite (which I LOVE, btw) and I picked up a used copy. Its sorta strange running around town and seeing signs of the person who was there before. Apparently everyone lives in one house now, though?