99c or $2.99. $2.99 or 99c. It's the Beatles or the Stones, Lampard or Gerrard of the ebook world.
Everyone's got an opinion, and a lot of people confuse their opinion with The One True Way. I think so much might depend on context that there isn't One True Way.
It's interesting though to read the argument for either side when it's well put, and I'll link to one or two as I come across them. John Rickards puts a good case here for $2.99.