score:5
The prices you're seeing are very high due to a combination of factors:
If you're not happy with what Bangkok Airways is charging, your alternative is to cross over to the mainland by ferry (~90 min) and either continue to Bangkok by cheap domestic flight from any of Surat Thani, Nakhon Si Thammarat or Chumphon, or take a cheap bus across to Phuket. Wikivoyage has the full scoop.