I'm about to do the same job on my boat, Stu...
Have decided to use a busbar for earthing and a splash-proof 6-way spade type fuse box for all the power connections. This way only one earth wire and one power wire from the batteries so can make things nice and tidy (hopefully). The fuse box will be hidden away under the helm station so highly unlikely to get wet, therefore I think the splash-proof type should be adequate for my needs..
The busbar was $19 and the fusebox was $39.95 from Smart Marine. The biggest cost was buying heavier cable (4mm tinned) for the main wiring. From memory, I think this was $10/meter or thereabouts and then a few extra bucks for appropriate sized terminals etc...
I'll still be using my original switch panel and will make fresh connections from/to the fuse box...
Semper in excreta sumus, solum profundum variat....