Some day I might just plunder the big island meself!
Be observant of beach use, grid it, dig it all but iron (Jewelry mode will do the trick) and be persistent. When you're diggin' pull tabs and nickles, arrrrrg, you're in the zone, bud. Before you know it, you will see loot in your scoop!
When you find it, be vague concerning locations (especially locals) but upload sparkly, clear, close-up photos. It gets our blood pumpin' donchaknow.
Your 150 should pay for itself right off (I'm serious), if you put some time in. Eventually, you can think of upgrading to a good water machine. In the meantime, learn your present machine and get all you can get out of it. Be confident that it is a decent machine.
Best of luck, welcome aboard. Be sure to keep us all posted. We might just need a contact in Paradise someday! <><
aj