I am flying into Honolulu then need to go to Maui.?

After I arrive in Honolulu I need to then fly to Kahalui, Maui or Kapalua, W.Maui It seems kinda expensive to book the leg to Maui online. Am I better off waiting until I get to Honolulu then buy my ticket to Maui? What is the best airline to search for the jog over to Maui? What am I looking at paying? When I was there last year it was only $30 to Maui and booking from the mainland to HNL then to Maui is coming up expensive. Please help