I posted some facts about public transport at https://www.expat.com/forum/viewtopic.php?id=323240
Keep in mind:
1). No US$100 and US$50 bills are accepted island wide.
2). Always have EC Dollar coins ready when getting off the bus. It is frowned upon to hand the bus driver EC$100 or EC$50 bills expecting to get change back.
3). Bus fares increase only with the Ministry of Transportation's approval. Inter-city bus fares range from EC$1.50 to $3.50
4). From Castries to Micoud, Soufirere, Vieux Fort = EC$8 / one way trip.
5). There is no bus route going around the island.
You can go west Castries -> Soufriere (changing buses) -> Vieux fort or
east Castries -> Vieux Fort.
Busses in the south: Vieux Fort -> Soufriere and back, which do not reach Castries.
6). Buses are aplenty from Monday to Friday, much fewer on Saturdays and very few on Sundays and public holidays. This is island life, not New York.
Buses are 14-seat, some have A/C some don't. Buses never leave the terminal unless all the seats are taken.
7). Buses are safe, and the drivers are professionals. There are much fewer accidents involving buses drivers than the rest of motorists.
There is no such kiosk from where you can buy bus tickets, and there is no such thing like weekly/monthly pass or frequent traveler pass.
You pay the driver who might be the bus owner or working for the bus owner. Talk to the driver first to eliminate any problem later.
When planning your trip always ask 1-2 persons first or you may come across unpleasant surprises on the road.
