I'd find the least expensive unit that you can add free charts too. (If you have a limited area of operation you could add way points to any GPS for sand bars, buoys, put ins etc.... Basic coast lines should already be included.) There are usually about 100 different icons so you won't have to add text to know the difference between a buoy, a rock or sandbar. So a unit that costs $100 to $150 would do what you need.

NOAA has free charts that are exactly the same as the ones Garmin and others sell for hundreds of dollars.
But how to add them to a GPS.....? Not sure if there are free charts for Fiji.

On my iPad I have NaviPad US app that I paid $5.99 for and then downloaded all the charts for the West Coast, Hawaii for free. The GPS in an iPad or iPhone is based on cell phone towers, not GPS satellites--so it's of little use on the water. (Supposedly smart phones are killing the GPS business. I personally think buggy software, terrible design (my Garmin nightmares (see below)) and adding cameras and widgets instead of work flow and reliability have killed the GPS business. I love a GPS but haven't had one for a couple of years because with every improvement they screw something up.

If no one has a definitive answer I always read the negative reviews, filter out the cranks (I'm probably borderline), and you'll get a pretty good idea of how these units actually perform. REI has good reliable reviews, but a limited range of brands, and less in the store than on their web site.

I've had two Garmin units. Both had problems that made them more trouble than they were worth.
I purchased Garmins because they were the only ones that could connect to my Apple computer without a lot of hassle.
The first was a 76 CS color screen--which is pretty useless in bright sunlight. I dropped it two feet and the glass cracked.
It stopped working after a year or so.
I then bought their Colorado model with Blue charts (basically NOAA charts)
I kayak so the charts weren't as useful as I thought they would be. For power boating, because you can cover a larger area, charts
will be more useful. ALL GPS units can direct you back to your put in, or to a way point. (In the fog they don't work fast enough to give you a high confidence of where you are pointing, but after a minute or two you can see your heading in the track line.)

Changing batteries in the Garmin Colorado was a nightmare. The back wouldn't come off without a pry tool.
A set of batteries lasted about 15 hours, so it would usually die in the middle of a 3-4 hour kayak paddle. Batteries are expensive so you don't want to replace them until you need to. I decided that I would have to be able to change the batteries on the water or the unit was worse than useless. I thought I had a workable method, but the first time I tried it, the thing shot over the side--they don't float and step one to change batteries is remove the part with the clip. Stupid stupid stupid. (I've got a Great Auk that is not at all tippy)
Good riddance to bad junk.. Relying on a device that is isn't reliable is more dangerous than not having it.