My first system was just a few years ago (04) in a 1988 Jeep Wrangler.
(4) Best Buy pioneer speakers. 6x9's and 4x6's
(2) Pioneer 10's, base model.
(2) Pyramid amplifiers, much less than 100w rms a piece.
I had the rear 6x9's amped and the front 4x6's running off the head unit.
Here's a pic of the sub box, which I built out of 5/8ths particle board. This is in my Cherokee, as I don't have any pictures of the system in my wrangler. The top was 8" deep and the bottom 11" to achieve 1 cube per sub, since the back seat of a wrangler is angled. It was a pretty pimp box IMO.