In Canada we have Mark's Work Warehouse, and Workwear World... they often have pretty decent foul weather sets for far less than Gill/Gull/HH prices.. and unless extended offshore trips are planned I think these are cost effective.
Everything leaks eventually - these sets cost around $150, often on sale for less.. do the math...
When Mustang first came out with their 'cruiser suits' ( non-survival 'overalls') we all bought them, they provided insulation, floatation all in one.. but soon found them to be too restrictive, often too warm (esp when actually 'doing' anything) and it was either 'all or nothing'. We went to layers, pants and jacket with the ability to adjust on the fly to the conditions.. esp racing, for the beat you needed more, but it was quickly too much on the runs. Those suits became personal suanas.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"