Capral is a good place to look for any Aluminium material you may need, but consider what you are making and it's use. I say this because after you make your part your widget may require further processing like Heat ageing process to align the crystaline structure etc... The various processes available are for ageing/hardening/protective coating etc... to make the end product suitable for it's intended use. Think of safety, an example is the cheap billet stuff that comes out of China, it may look alright, but because of poor quality material grade to start with and no hardening process they usually don't last for too long. My 2c worth