[gregoryx]

Where are you guys getting your cable used for powering the lights, 12V outlets etc?

Speaker wire. Decent quality but not expensive. #18 for small puck lights, #12 or #10 for outlets, etc.

18 gauge
14 gauge
12 gauge
10 gauge

Have also used in-wall speaker wire - nice sheath. And the marine-grade stuff - just for 120VAC.