There is taxi service to and from the Airport. Taxi service is extremely expensive in town, most visitors rent cars.
The Hele-On Bus
This Island bus services address the transportation needs of Hawai’i residents to make commuting to and from work easier. There are stops all around Hawai’i Island, with service between Kona and Hilo. Official website: www.heleonbus.org
The Kona Trolley
The Kona Trolley is the local area shuttle that makes two alternating loops around Kona area attractions. It does a shorter loop to retail/restaurant areas and a longer one to nearby beaches; service is limited, so make sure you have a copy of the schedule.
If you plan on just hanging around and visiting Kailua Village, you can easily do it on foot. It's small and compact. From condo D-26, head north on frontage road Kahakai for a quick walk to restaurants and cafés, souvenir shops, the farmers market and a few historic sites.