Just come back from the Solomons but we stayed in the Western Province. Honiara is probably the worst part of the Solomons. I would suggest going down to the Yacht club (not like Aussie yacht clubs) and ask there.
The locals work for around 90c to $1.20 per hr but fuel costs similar to here. Quite often they will give you an hourly rate to hire the boat + fuel. Boats are a vital way of getting around in the Solomons so if you can find a local with boat pretty good chance of hiring a boat a driver for the right price. The majority of powered boats are fibreglass long boats, if you venture to the back of the local markets you will se maybe 20 or 30 of them as the people selling in the market come from far and wide.
If you get opportunity to get to the islands other than Honiara take it as this is a magical part of the world.