In Port Vila the buses are van and mini-buses with a red B on the left side of the number plate. They largely traverse the main road take you directly to your destination. There are no scheduled services and are perhaps best thought of as cheap, but shared taxis. Wave at them to stop one heading in the direction you want to go. They are plentiful within the city and outside the city you can usually arrange for a bus to meet you at a particular time. If one looks full, just wait for the next one. The buses are used by locals, but are very friendly, cheap, and easy to use by tourists. Fares are usually calculated per person. The cost is usually 150 vatu per person unless you are traveling a longer distance, e.g. Mele Cascades - in which case expect to pay 200 vatu per person. There are significantly fewer buses on the road on Sundays.
Taxis are plentiful within Port Vila. Fare is calculated per taxi. There are standard fares for journeys to and from the airport to most accommodation around Port-Vila a list of which should be available in the arrivals section of the airport. 1500VT to the city centre. Around Port Vila, taxi's can be hailed for journeys. Price is usually around 500vt for short journeys, however if planning on a longer journey, negotiate with the driver on the price.
There are markets selling a variety of local goods such as fruit and vegetables. They close on Sundays unless there is a cruise ship in port.
Duty free alcohol and cigarettes are cheap in Port Vila. Buy your duty free before going to the airport as the airport duty free prices are slightly higher and the range not as great.
Alcohol is reasonably expensive in Port Vila. Expect to pay between 300VT and 500VT for a local beer or between 400VT and 600VT for imported beers.