I get that, and totally get where you're coming from. I bought all mine off of Amazon. If you buy marine grade connectors, they should be good. Marine grade has a glue inside the heat shrink that creates a waterproof connection.Scanning the web, but I don't know a good retailer from a bad one.
Don't really feel like taking my chances with bargain products off Ebay or Amazon, for something safety-related like this...
I have been using Digikey and Mouser .. a let over habit from a former life..