I just looked on ebay and OMG eBay: BARBIE LOVES MAC COLLECTORS BARBIE DOLL BNIB !!! (item 300081308983 end time Feb-23-07 17:57:41 PST)
I would say there is over a 100 or more on there for sale. I can't believe the prices makes me kick myself that I didn't get more than one.
I do see that they are now selling Barbie Loves MAC products on Nordstrom.com. So if you see things sold out on the official MAC site try Nordstoms. I did not see the Barbie online but not sure if they are selling that at a Nordstroms store.