If you are looking for good metal at good prices, check out Midwest Steel and Aluminum | Buy Metal Online | Online Metal Supplier and Random Aluminum Pieces & Parts | Aluminum Flat Bar & Tooling Plate Suppliers - Howard Precision Metals Inc. Both have a huge assortment of metals and fair prices. Their products are in top condition and arrive fast. The random rack to Howard’s is a great place to pick up stock for projects from .125" to over 4" thick. We use either or both of these places weekly for production runs and they are both great to work with. Howard’s random rack is a bit cheaper overall and the more you order, the better the shipping comes out. But you will be hard pressed to get the same size stock week to week so setting up production runs on plates of stock is not as easy as ordering a standardized stock size from Midwest and running the same Gcode job after job when you change out plates.
Try to get the same alloy and temper so your feeds and speeds can move from one job to the next without issues. If you try to cut 5082 at the same feeds and such as 6061 T6, you will find issues and start to dislike milling aluminum dry.
It can not be said enough, keep the chips clear on aluminum while you mill. Air blasting will do a fine job if you are able to keep a steady firm air-stream at right angels to your cutter.