Much Better to be RED than Dead

Oh, that crazy Bono and his "help the world" schemes. This time the U2 frontman/world savior is fronting an effort by RED, the charity he founded with Bobby Shriver to raise money for the Global Fund and thereby fight aids in africa. RED works with product manufacturers (Motorola, Apple, Armani, Converse and the GAP are all on board) to create branded versions of popular products (RAZRs, iPod, Chuck Taylors, etc.). Buy one and a portion of the purchase price goes to fighting AIDS.
Earlier today, Bono launched the iPod Nano (PRODUCT) Red (aka the red Nano; the whole "(PRODUCT) Red" thing is supposed to be an embrace, according to the RED FAQ) on the Oprah Winfrey show. The new iPod is exactly the same as all of the other Nanos in the current generation, except for the candy red shell and the $10 donation that goes from the sale of every one of these iPods towards fighting AIDS.
While I certainly applaud the effort behind this initiative, I do wonder why the donation is only $10, or 5% of the Nano's $200 price tag. Are the margins for creating iPods really that small that Apple can't afford to give away more? Will the company hit some sort of charitable contribution limit if they make the donation too big? How far does $10 really go in fighting AIDS?