This was confusing to me as well. I have a CNC router, and I, along with most readers, would probably equate these things. For all intents and purposes, CNC === CNC router, or at the very least expensive, uncommon equipment in a home shop.
I haven't bought much aluminum lately, but I used to go to Alco in San Leandro (Bay Area). Steel I get from Bay Steel, which is right next to my shop. it might be up to $.90 (?)