Waytek is a seller of a VAST array of electrical goods that may interest many members of and visitors to this forum.  I believe they have a minimum order amount, but their prices are great for DIY people.  I really can't describe all the stuff they have, and I feel the website is (currently) well organized and easy to navigate.  I sourced HELLA relays and very heavy duty duty pigtails from them for some projects.  If you can't easily source electrical components locally, I suggest you at least give Waytek a look, even just to get a feel for pricing.

There is a lot of what seems like good advice at the below link, such as selecting circuit breakers, and extending the life of automotive wiring and connections.  Many blogs here for learning.

https://info.waytekwire.com/blog