Hi Nick,
Here’s a couple links to some on AliExpress
M12:
C$ 1.87 | M12 sensor connector waterproof maleandfemale plug screw threaded coupling 4 5 8 Pin A type sensor connectors
M8:
C$ 2.22 | M8 sensor connector waterproof maleandfemale plug straight angle screw threaded coupling 3pin 4 pin
I went this route mostly because of size, and like you said about soldering outside. I needed something with a small diameter and with screw down terminals for my application. It also needed to work with a round cable.
I ended up getting an M8 model I found, modified and branded to sell with my lights. I’m still in the process of getting them certified.
If you’re not limited by size, the larger ones like the M12 can handle more current.
Another option I found that might work is from TE Connectivity. They make a connector called Coolsplice. It doesn’t work for my application, but the samples I got were pretty good. They are also a pretty good price. They have a bunch of different models depending on what you need. Here’s a 2 wire 18awg model.