Home Depot, Rona and Canadian Tire store do carry some stock for emergency use. Caution, they are not cheap.
Generally speaking, they are not bare stock for milling purposes. All aluminum material are already anodized in good finish. The sticker indicates material are imported by H. Paulin & Company Limited and stock originated from China and Taiwan.
Previously mentioned from another post, we have a bench sized mini-mill for quick prototyping and parts creation. Back then we purchased some scales and setup DRO on this milling machine but never have a chance to document the process for sharing.
Yeah!! Our subscription to Flickr and WordPress now allow us to blog about the process with pictures. Follow link to Flickr Photo set of Mini-mill DRO pictures
The bench top milling machine we used in R&D is a Harbor Freight Two-Speed Variable Bench Mill/Drill Machine, purchased many years ago and went through many customization throughout the years of usage.