Re: Electrical connectors?
+1 on Global Metrics for fasteners, did not know they did connectors!
Re connectors, there's a lot of personal preference in selecting them. I have crimpers and connector sets for Weatherpack, Metripack and AMP. Weatherpack is decent but is limited to 10A IIRC. Metripack 280 is 20A IIRC. Both of those are bulky IMO but fine for automotive and a lot of modern stuff uses it anyway.
The nice crimpers will do the whole crimp at once vs the cheap ones, but at 10x the price. My current favorite crimpers are the Pressmaster interchangeable series.
IWISS are my favorites for cheap crimpers- Metri and Weatherpack for $15.99
Make sure you buy the relevant de-pinning tools.
My next foray is into Deutsch, as they have good current carrying capacity for the physical size and the crimping tools are reasonably priced.
There are tons of cheap Chinese knockoff connectors on Amazon for all the connector types. I've had decent success with them but they're definitely not OEM quality! YMMV