A sticky I think that is needed on this forum would be a list of where to buy raw materials and who has the best deal. Here's a few to start (note not all posted here are verified, please call and make your own decision, feel free to add a verify if you've order with success)
Metals
Metal Express
Online Metals
McMaster Carr
Enco
MSC
Industrial Metal Sales
Plastics
U.S. Plastic Corp
MSC
McMaster Carr
Online Metals
Tap Plastics
Composites
Fibre Glast
ACP Composites
US Composites
Anyone here using http://www.discountsteel.com ?
Seems to be very affordable aluminum raw materials
.